Alphabetic List of Keywords

Note 1: Additional components of CPMD input files that do not fit into the following list are explained in the succeeding section 11.5.

Note 2: Keywords for the &QMMM section of the CPMD/Gromos QM/MM-Interface code are not listed here but in section 9.16.2.

ACM0

Section: &DFT

Add exact exchange to the specified FUNCTIONAL according to the adiabatic connection method 0. [134,135] This only works for isolated systems and should only be used if an excessive amount of CPU time is available.

ACM1

Section: &DFT

Add exact exchange to the specified FUNCTIONAL according to the adiabatic connection method 1. [136,135] The parameter is read from the next line. This only works for isolated systems and should only be used if an excessive amount of CPU time is available.

ACM3

Section: &DFT

Add exact exchange to the specified FUNCTIONAL according to the adiabatic connection method 3. [136,135] The three needed parameters are read from the next line. This only works for isolated systems and should only be used if an excessive amount of CPU time is available.

ALEXANDER MIXING

Section: &CPMD

Mixing used during optimization of geometry or molecular dynamics. Parameter read in the next line.
Default value is 0.9

ALPHA

Section: &PATH

Smoothing parameter for iterating the string (see [128]).
Default value is 0.2

ALLTOALL {SINGLE,DOUBLE}

Section: &CPMD

Perform the matrix transpose (AllToAll communication) in the 3D FFT using single/double precision numbers. Default is to use double precision numbers.

ANDERSON MIXING $N=n$

Section: &CPMD

Anderson mixing for the electronic density during self-consistent iterations. In the next line the parameter (between 0 and 1) for the Anderson mixing is read.
Default is 0.2 .
With the additional option $N=n$ a mixing parameter can be specified for different threshold densities. $n$ different thresholds can be set. The program reads $n$ lines, each with a threshold density and an Anderson mixing parameter.

ANGSTROM

Section: &SYSTEM

The atomic coordinates and the supercell parameters and several other parameters are read in Ångstroms.
Default is atomic units which are always used internally. Not supported for QMMM calculations.

ANNEALING {IONS,ELECTRONS,CELL}

Section: &CPMD

Scale the ionic, electronic, or cell velocities every time step. The scaling factor is read from the next line.

ATOMIC CHARGES

Section: &ATOMS

Changes the default charge (0) of the atoms for the initial guess to the values read from the next line. One value per atomic species has to be given.

AVERAGED POTENTIAL

Section: &PROP

Calculate averaged electrostatic potential in spheres of radius Rcut around the atomic positions.
Parameter Rcut is read in from next line.

BECKE BETA

Section: &DFT

Change the $\beta$ parameter in Becke's exchange functional [137] to the value given on the next line.

BENCHMARK

Section: &CPMD

This keyword is used to control some special features related to benchmarks. If you want to know more, have a look in the source code.

BERENDSEN {IONS,ELECTRONS,CELL}

Section: &CPMD

Use a simple Berendsen-type thermostat[28] to control the respective temperature of ions, electrons, or cell. The target temperature and time constant $\tau$ (in a.u.) are read from the next line.

These thermostats are a gentler alternative to the TEMPCONTROL mechanism to thermalize a system. For production runs, please use the corresponding NOSE thermostats, as the Berendsen scheme does not represent any defined statistical mechanical ensemble.

BFGS

Section: &CPMD

Use a quasi-Newton method for optimization of the ionic positions. The approximated Hessian is updated using the Broyden-Fletcher-Goldfarb-Shano procedure [138].

BLOCKSIZE STATES

Section: &CPMD

Parameter read in from next line.
NSTBLK
Defines the minimal number of states used per processor in the distributed linear algebra calculations.
Default is to equally distribute states over all processors.

BOGOLIUBOV CORRECTION [OFF]

Section: &CPMD

Computes the Bogoliubov correction for the energy of the Trotter approximation or not.
Default is no Bogoliubov correction.
The keyword has to appear after FREE ENERGY FUNCTIONAL.

BROYDEN MIXING

Section: &CPMD

Parameters read in from next line.
BROYMIX, ECUTBROY, W02BROY, NFRBROY, IBRESET
These mean:

BROYMIX:

Initial mixing, e.g. $0.1$ ; default value is 0.5

ECUTBROY:

Cutoff for Broyden mixing. DUAL*ECUT is the best choice and the default

W02BROY:

$w_0^2$ parameter of Johnson [139]. Default 0.01

NFRBROY:

Number of Anderson mixing steps done before Broyden mixing. Default is 0

IBRESET:

Number of Broyden vectors. $5$ is usually a good value and the default.

You can also specify some parameters with the following syntax:
[BROYMIX=BROYMIX] [ECUTBROY=ECUTBROY]
[W02BROY=W02BROY] [NFRBROY=NFRBROY]
[IBRESET=IBRESET]
Finally, you can use the keyword DEFAULT to use the default values.

CELL {ABSOLUTE, DEGREE, VECTORS}

Section: &SYSTEM

The parameters specifying the super cell are read from the next line. Six numbers in the following order have to be provided: $a$ , $b/a$ , $c/a$ , $\cos \alpha$ , $\cos \beta$ , $\cos \gamma$ . For cubic phases, $a$ is the lattice parameter. CPMD will check those values, unless you turn off the test via CHECK SYMMETRY. With the keyword ABSOLUTE, you give $a$ , $b$ and $c$ . With the keyword DEGREE, you provide $\alpha$ , $\beta$ and $\gamma$ in degrees instead of their cosine. With the keyword VECTORS, the lattice vectors $a1$ , $a2$ , $a3$ are read from the next line instead of the 6 numbers. In this case the SYMMETRY keyword is not used.

CENTER MOLECULE [OFF]

Section: &CPMD

The center of mass is moved/not moved to the center of the computational box in a calculation with the cluster option. This is only done when the coordinates are read from the input file.

CENTROID DYNAMICS

Section: &PIMD

Adiabatic centroid molecular dynamics, see Ref. [140,141,142] for theory and details of our implementation, which yields quasiclassical dynamics of the nuclear centroids at a specified temperature of the non-centroid modes. This keyword makes only sense if used in conjunction with the normal mode propagator via the keyword NORMAL MODES and FACSTAGE $>1.0$ and WMASS $=1.0$ . The centroid adiabaticity control parameter FACSTAGE, which makes the non-centroid modes artificially fast in order to sample adiabatically the quantum fluctuations, has to be chosen carefully; note that FACSTAGE  $= 1/\gamma$ as introduced in Ref. [142] in eq. (2.51).

CG-ANALYTIC

Section: &RESP

The number of steps for which the step length in the conjugate gradient optimization is calculated assuming a quadratic functional E(2) (quadratic in the linear response vectors). No accuracy impact, pure convergence speed tuning.
Default value is 3 for NMR and 99 otherwise.

CG-FACTOR

Section: &RESP

The analytic length calculation of the conjugate-gradient step length yields in general a result that is slightly too large. This factor is used to correct for that deficiency. No accuracy impact, pure convergence speed tuning.
Default is 0.8 .

CHANGE BONDS

Section: &ATOMS

The buildup of the empirical Hessian can be affected.
You can either add or delete bonds. The number of changed bonds is read from the next line. This line is followed by the description of the bonds. The format is
{ ATOM1 ATOM2 FLAG} .
ATOM1 and ATOM2 are the numbers of the atoms involved in the bond. A FLAG of $-1$ causes a bond to be deleted and a FLAG of $1$ a bond to be added.
Example:

2
1	2	+1
6	8	-1

CHARGES

Section: &PROP

Calculate atomic charges. Charges are calculated according to the method of Hirshfeld [143] and charges derived from the electrostatic potential [144].

CHARGE

Section: &SYSTEM

The total charge of the system is read from the next line.
Default is 0 .

CHECK MEMORY

Section: &CPMD

Check sanity of all dynamically allocated arrays whenever a change in the allocation is done. By default memory is checked only at break points.

CHECK SYMMETRY [OFF]

Section: &SYSTEM

The precision with which the conformance of the CELL parameters are checked against the (supercell) SYMMETRY is read from the next line. With older versions of CPMD, redundant variables could be set to arbitrary values; now all values have to conform. If you want the old behavior back, you can turn the check off by adding the keyword OFF or by providing a negative precision. Default value is: 1.0e-4

CLASSICAL CELL [ABSOLUTE, DEGREE]

Section: &SYSTEM

Not documented.

CLASSICAL TEST

Section: &PIMD

Test option to reduce the path integral branch to the classical code for the special case $P=1$ in order to allow for a one-to-one comparison to a run using the standard branch of CPMD. It works only with primitive propagator, i.e. not together with NORMAL MODES, STAGING and/or DEBROGLIE CENTROID.

CLASSTRESS

Section: &CPMD

Not documented.

CLUSTER

Section: &SYSTEM

Isolated system such as a molecule or a cluster. Same effect as SYMMETRY 0, but allows a non-orthorhombic cell. Only rarely useful.

CMASS

Section: &CPMD

The fictitious mass of the supercell in atomic units is read from the next line.
Default value is to use the total mass of all atoms in the system.

COMPRESS [WRITEnn]

Section: &CPMD

Write the wavefunctions with nn bytes precision to the restart file.
Possible choices are WRITE32, WRITE16, WRITE8 and WRITEAO.
WRITE32 corresponds to the compress option in older versions. WRITEAO stores the wavefunction as a projection on atomic basis sets. The atomic basis set can be specified in the section &BASIS. If this input section is missing a default basis from Slater type orbitals is constructed. See section 11.5.3 for more details.

CONDUCTIVITY

Section: &PROP

Computes the optical conductivity according to the Kubo-Greenwod formula

$$\sigma(\omega) = \frac{2 \pi e^2}{3m^2 V_\mathrm{cell}} \frac{1}{... ...p}} \vert\psi _j \rangle \vert^2 \delta(\epsilon _i -\epsilon_j - \hbar \omega)$$

where $\psi _i$ are the Kohn-Sham eigenstates, $\epsilon_i$ their corresponding eigenvalues, $f_i$ the occupation number and the difference $f_i-f_j$ takes care of the fermionic occupancy. This calculation is executed when the keyword PROPERTIES is used in the section &CPMD. In the section &PROP the keyword CONDUCTIVITY must be present and the interval $\Delta \omega$ for the calculation of the spectrum is read from the next line. Note that, since this is a PROPERTIES calculation, you must have previously computed the electronic structure of your system and have a consistent RESTART file ready to use.

Further keyword: STEP=0.14, where (e.g.) 0.14 is the bin width in eV of the $\sigma(\omega)$ histogram if you want it to be different from $\Delta \omega$ . A file MATRIX.DAT is written in your working directory, where all the non-zero transition amplitudes and related information are reported (see the header of MATRIX.DAT). An example of application is given in Ref. [145].

CONFINEMENT POTENTIAL

Section: &ATOMS

The use of this label activates a spherical gaussian confinement potential in the calculation of the form factor of pseudopotentials. In the next line(s) two parameters for each atomic species must be supplied: the amplitude $\alpha$ and the cut off radius $r_c$ . The gaussian spherical amplitude is computed as $A=\pi ^{3/2}r_c^3\cdot \alpha$ and the gaussian confinement potential reads

$$V(\mathbf{G}) = \sum_\mathbf{G} A \cdot \vert\mathbf{G}\vert\cdot e^{-G^2r_c^2/4}$$

being G the G-vectors, although in practice the loop runs only on the G-shells $G=\vert\mathbf{G}\vert$ .

CONJUGATE GRADIENTS [ELECTRONS, IONS, NOPRECONDITIONING]

Section: &CPMD

For the electrons, the keyword is equivalent to PCG. The NOPRECONDITIONING parameter only applies for electrons. For the ions the conjugate gradients scheme is used to relax the atomic positions.

CONSTANT CUTOFF

Section: &SYSTEM

Apply a cutoff function to the kinetic energy term [147] in order to simulate constant cutoff dynamics. The parameters $A$ , $\sigma$ and $E_o$ are read from the next line (all quantities have to be given in Rydbergs).

$$G^2 \to G^2 + A \left[ 1 + \mbox{erf} \left( {\frac{\frac{1}{2} G^2 - E_o}{\sigma}} \right) \right]$$

CONSTRAINTS

Section: &ATOMS

With this option you can specify several constraints and restraints on the atoms. (see section 11.5.2 for more information on the available options and the input format). This section of the input has to be terminated by a line containing END CONSTRAINTS.

CONVERGENCE [ADAPT, ENERGY, CALFOR, RELAX, INITIAL]

Section: &CPMD

The adaptive convergence criteria for the wavefunction during a geometry optimization are specified. For more information, see [146]. The ratio TOLAD between the smallest maximum component of the nuclear gradient reached so far and the maximum allowed component of the electronic gradient is specified with CONVERGENCE ADAPT. This criterion is switched off once the value TOLOG given with CONVERGENCE ORBITALS is reached. By default, the adaptive gradient criterion is not active. A reasonable value for the parameter TOLAD is 0.02.
If the parameter TOLENE is given with CONVERGENCE ENERGY, in addition to the gradient criterion for the wavefunction, the energy change between two wavefunction optimization cycles must be smaller than the energy change of the last accepted geometry change multiplied by TOLENE for the wavefunction to be considered converged. By default, the adaptive energy criterion is not active. It is particularly useful for transition state search with P-RFO, where the trust radius is based on the quality of energy prediction. A reasonable value for TOLENE is 0.05.
To save CPU time, the gradient on the ions is only calculated if the wavefunction is almost converged. The parameter TOLFOR given with CONVERGENCE CALFOR is the ratio between the convergence criteria for the wavefunction and the criteria whether the gradient on the ions is to be calculated. Default value for TOLFOR is 3.0 .
If the wavefunction is very slowly converging during a geometry optimization, a small nuclear displacement can help. The parameter NSTCNV is given with CONVERGENCE RELAX. Every NSTCNV wavefunction optimization cycles, the convergence criteria for the wavefunction are relaxed by a factor of two. A geometry optimization step resets the criteria to the unrelaxed values. By default, the criteria for wavefunction convergence are never relaxed.
When starting a geometry optimization from an unconverged wavefunction, the nuclear gradient and therefore the adaptive tolerance of the electronic gradient is not known. To avoid the full convergence criterion to be applied at the beginning, a convergence criterion for the wavefunction of the initial geometry can be supplied with CONVERGENCE INITIAL. By default, the initial convergence criterion is equal to the full convergence criterion.

CONVERGENCE [ORBITALS, GEOMETRY, CELL]

Section: &CPMD

The convergence criteria for optimization runs is specified.
The maximum value for the biggest element of the gradient of the wavefunction (ORBITALS), of the ions (GEOMETRY), or the cell (CELL) is read from the next line.
Default values are 10$^{-5}$ for the wavefunction, 5$\times$ 10$^{-4}$ for the ions and 1.0 for the cell. For diagonalization schemes the first value is the biggest variation of a density component. Defaults are 10$^{-3}$ and 10$^{-3}$ .

CONVERGENCE

Section: &LINRES

Convergence criterion for linear response calculations.
Default value is 10$^{-5}$ .

CONVERGENCE

Section: &RESP

Convergence criterion on the gradient $\delta E/\delta \psi^*$ Default value is 10$^{-5}$ .

CORE SPECTRA

Section: &PROP

Computes the X-ray adsorption spectrum and related transition matrix elements according to Ref. [148]. This calculation is executed when the keyword PROPERTIES is used in the section &CPMD. In the section &PROP the keyword CORE SPECTRA must be present and the core atom number (e.g. 10 if it is the 10$th$ atom in your list) and core level energy (in au) are read from the next line, while in the following line the $n$ and $l$ quantum numbers of the selected core level, along with the exponential factor $a$ of the STO orbital for the core level must be provided. In the case of $1s$ states, the core orbital is reconstructed as

$$\psi _{1s}(r) = 2 a^{\frac{3}{2}} r \cdot \exp (-a\cdot r)$$

and it is this $a$ value in au that must be supplied in input. As a general rule, first-row elements in the neutral case have the following $a$ values: B (4.64), C (5.63), N (6.62), O (7.62). For an excited atom these values would be of course a bit larger; e.g. for O it is 7.74453, i.e. 1.6 % larger. Since this is a PROPERTIES calculation, you must have previously computed the electronic structure of your system and have a consistent RESTART file ready to use. A file XRAYSPEC.DAT is written in your working directory, containing all the square transition amplitudes and related information, part of which are also written in the standard output. Waring: in order to use this keyword you need special pseudopotentials. These are provided, at least for some elements, in the PP library of CPMD and are named as *_HOLE.psp

COUPLINGS {FD=$\epsilon$ ,PROD=$\epsilon$ } [NAT]

Section: &SYSTEM

Calculate non-adiabatic couplings [126] using finite differences (FD and PROD are two different finite-difference approximations). The displacement $\epsilon$ is expected in atomic units. If NAT=$n$ is given, the coupling vector acting on only a subset of $n$ atoms is calculated. In this case, a line containing $n$ atom sequence numbers is expected. See COUPLINGS NSURF.

COUPLINGS LINRES {BRUTE FORCE,NVECT=$n$ } [THR,TOL]

Section: &SYSTEM

Calculate non-adiabatic couplings [126] using linear-response theory. With BRUTE FORCE, the linear response to the nuclear displacements along all Cartesian coordinates is calculated. With NVECT=$n$ , at most $n$ cycles of the iterative scheme in [126] are performed. However, the iterative calculation is also stopped earlier if its contribution to the non-adiabatic coupling vector is smaller a given tolerance (TOL= $C_{\mathrm{tol}}$ ). In the case of the iterative scheme, also the option THR can be given, followed by three lines each containing a pair of a threshold contribution to the non-adiabatic coupling vector and a tolerance for the linear-response wavefunction (see [126]). Do not forget to include a &LINRES section in the input, even if the defaults are used. See COUPLINGS NSURF.

COUPLINGS NSURF

Section: &SYSTEM

Required for non-adiabatic couplings: the Kohn-Sham states involved in the transition. For the moment, only one pair of states makes sense, NSURF=1. On the following line, the orbital numbers of the two Kohn-Sham states and a weight of 1.0 are expected. For singlet-singlet transitions, the ROKS-based Slater transition-state density (LOW SPIN EXCITATION LSETS) should be used. For doublet-doublet transitions, the local spin-density approximation (LSD) with the occupation numbers (OCCUPATION, NSUP, STATES) of the corresponding Slater transition-state density should be used.

CUBECENTER

Section: &PROP

Sets the center of the cubefiles produced by the CUBEFILE flag. The next line has to contain the coordinates of the center in Bohr or Angstrom, depending on whether the ANGSTROM keyword was given. Default is the geometric center of the system.

CUBEFILE ORBITALS,DENSITY HALFMESH

Section: &PROP

Plots the requested objects in .CUBE file format. If ORBITALS are demanded, the total number as well as the indices have to be given on the next and second next line. HALFMESH reduces the number of grid points per direction by 2, thus reducing the file size by a factor of 8.

CUTOFF [SPHERICAL,NOSPHERICAL]

Section: &SYSTEM

The cutoff for the plane wave basis in Rydberg is read from the next line. The keyword SPHERICAL is used with k points in order to have $\vert g + k\vert^2 < E_{cut}$ instead of $\vert g\vert^2 < E_{cut}$ . This is the default.

DAMPING {IONS,ELECTRONS,CELL}

Section: &CPMD

Add a damping factor $f_{damp}(x) = - \gamma \cdot v(x)$ to the ionic, electronic, or cell forces in every time step. The scaling factor $\gamma$ is read from the next line. Useful values depend on the employed masses are generally in the range $5.0 \to 50.0$ .

Damping can be used as a more efficient alternative to ANNEALING for wavefunction, geometry or cell optimization (and particularly combinations thereof) of systems where the faster methods (e.g. ODIIS, PCG, LBFGS, GDIIS) fail to converge or may converge to the wrong state.

DAVIDSON DIAGONALIZATION

Section: &CPMD

Use Davidson diagonalization scheme.[149]

DAVIDSON PARAMETER

Section: &CPMD

This keyword controls the Davidson diagonalization routine used to determine the Kohn-Sham energies.
The maximum number of additional vectors to construct the Davidson matrix, the convergence criterion and the maximum number of steps are read from the next line.
Defaults are 10$^{-5}$ and the same number as states to be optimized. If the system has 20 occupied states and you ask for 5 unoccupied states, the default number of additional vectors is 25. By using less than 25 some memory can be saved but convergence might be somewhat slower.

DAVIDSON PARAMETER

Section: &TDDFT

The maximum number of Davidson iterations, the convergence criteria for the eigenvectors and the maximal size of the Davidson subspace are set. The three parameters ndavmax, epstdav, ndavspace are read from the next line.
Default values are 100 , 10$^{-10}$ and 10 .

DAVIDSON RDIIS

Section: &TDDFT

This keyword controls the residual DIIS method for TDDFT diagonalization. This method is used at the end of a DAVIDSON diagonalization for roots that are not yet converged. The first number gives the maximum iterations, the second the maximum allowed restarts, and the third the maximum residual allowed when the method is invoked.
Default values are 20 , 3 and $10^{-3}$ .

DEBROGLIE [CENTROID]

Section: &PIMD

An initial configuration assuming quantum free particle behavior is generated for each individual atom according to its physical mass at the temperature given in Kelvin on the following input line. Using DEBROGLIE each nuclear position obtained from the &ATOMS section serves as the starting point for a Gaussian Lévy walk of length $P$ in three dimensions, see e.g. Ref. [150]. Using DEBROGLIE CENTROID each nuclear position obtained from the &ATOMS section serves as the centroid (center of geometry) for obtaining the centroid (center of geometry) for obtaining the $P$ normal modes in three dimensions, see e.g. Ref. [151]. This option does only specify the generation of the initial configuration if INITIALIZATION and GENERATE REPLICAS are active. Default is DEBROGLIE CENTROID and 500 Kelvin.

DEBUG CODE

Section: &CPMD

Turn on very verbose output concerning subroutine calls for debugging purposes.

DEBUG FILEOPEN

Section: &CPMD

Turn on very verbose output concerning opening files for debugging purposes.

DEBUG FORCES

Section: &CPMD

Turn on very verbose output concerning the calculation of each contribution to the forces for debugging purposes.

DEBUG IO

Section: &CPMD

Turn on very verbose output concerning the reading and writing of restart files for debugging purposes.

DEBUG MEMORY

Section: &CPMD

Very verbose output concerning memory for debugging purpose.

DEBUG NOACC

Section: &CPMD

Do not read/write accumulator information from/to the RESTART file. This avoids putting timing information to the restart and makes restart files identical for otherwise identical runs.

DENSITY CUTOFF [NUMBER]

Section: &SYSTEM

Set the plane wave energy cutoff for the density. The value is read from the next line. The density cutoff is usually automatically determined from the wavefunction CUTOFF via the DUAL factor.
With the additional flag NUMBER the number of plane waves can be specified directly. This is useful to calculate bulk modulus or properties depending on the volume. The given energy cutoff has to be bigger than the one to have the required plane wave density number.

DIAGONALIZER {DAVIDSON,NONHERMIT,PCG} [MINIMIZE]

Section: &TDDFT

Specify the iterative diagonalizer to be used.
Defaults are DAVIDSON for the Tamm-Dancoff method, NONHERMIT (a non-hermitian Davidson method) for TDDFT LR and PCG (Conjugate gradients) for the optimized subspace method. The additional keyword MINIMIZE applies to the PCG method only. It forces a line minimization with quadratic search.
Default is not to use line minimization .

DIAGONAL [OFF]

Section: &HARDNESS

Not documented

DIFF FORMULA

Section: &LINRES

Number of points used in finite difference formula for second derivatives of exchange-correlation functionals. Default is two point central differences.

DIIS MIXING

Section: &CPMD

Use the direct inversion iterative scheme to mix density.
Read in the next line the number of previous densities (NRDIIS) for the mixing (however not useful).

DIIS MIXING [$N=n$ ]

Section: &CPMD

Like DIIS MIXING, but number of previous densities for the mixing can be specified as a function of the density.
$n$ different thresholds for the density can be set. The program reads $n$ lines with a threshold density and a NRDIIS number (number of previous densities for the mixing). Numbers NRDIIS have to increase. If the NRDIIS is equal to 0, Anderson mixing is used. Very efficient is to use Anderson mixing and subsequently DIIS mixing.

DIPOLE DYNAMICS {SAMPLE,WANNIER}

Section: &CPMD

Calculate the dipole moment [78,79] every NSTEP iteration in MD.
NSTEP is read from the next line if the keyword SAMPLE is present.
Default is every time step.
The keyword Wannier allows the calculation of optimally localized Wannier functions[85,91,123]. The procedure used is equivalent (for single k-point) to Boys localization.

The produced output is IONS+CENTERS.xyz, IONS+CENTERS, DIPOLE, WANNIER_CENTER and WANNIER_DOS. The localization procedure is controlled by the following keywords.

DIPOLE MOMENT [BERRY,RS]

Section: &PROP

Calculate the dipole moment.
Without the additional keywords BERRY or RS this is only implemented for simple cubic and fcc supercells. The keyword RS requests the use of the real-space algorithm. The keyword BERRY requests the use of the Berry phase algorithm.
Default is to use the real-space algorithm.

DISCARD [OFF,PARTIAL,TOTAL,LINEAR]

Section: &RESP

Request to discard trivial modes in vibrational analysis from linear response (both PHONON and LANCZOS).

OFF = argument for performing no projection
PARTIAL = argument for projecting out only translations (this is the default)
TOTAL = argument for projecting both rotations and translations
LINEAR = argument for projecting rotations around the $C-\infty$ axis in a linear molecule (not implemented yet).

DISTRIBUTED LINALG {ON,OFF}

Section: &CPMD

Perform linear algebra calculations using distributed memory algorithms. Setting this option ON will also enable (distributed) initialization from atomic wavefunctions using a parallel Lanczos algorithm [7]. Note that distributed initialization is not available with KPOINTS calculations. In this case, initialization from atomic wavefunctions will involve replicated calculations.

When setting LINALG ON the keyword BLOCKSIZE STATES becomes relevant (see entry). The number of BLOCKSIZE STATES must be an exact divisor of the number of STATES.

DISTRIBUTE FNL

Section: &CPMD

The array FNL is distributed in parallel runs.

DUAL

Section: &SYSTEM

The ratio between the wavefunction energy CUTOFF and the DENSITY CUTOFF is read from the next line.
Default is 4.
There is little need to change this parameter, except when using ultra-soft pseudopotentials, where the wavefunction cutoff is very low and the corresponding density cutoff is too low to represent the augmentation charges accurately. In order to maintain good energy conservation and have good convergence of wavefunctions and related parameters, DUAL needs to be increased to values of 6-10.
Warning: You can have some trouble if you use the DUAL option with the symmetrization of the electronic density.

DUMMY ATOMS

Section: &ATOMS

The definition of dummy atoms follows this keyword.
Three different kinds of dummy atoms are implemented. Type 1 is fixed in space, type 2 lies at the arithmetic mean, type 3 at the center of mass of the coordinates of real atoms.
The first line contains the total number of dummy atoms. The following lines start with the type label TYPE1, TYPE2, TYPE3.
For type 1 dummy atoms the label is followed by the Cartesian coordinates.
For type 2 and type 3 dummy atoms the first number specifies the total number of atoms involved in the definition of the dummy atom. Then the number of these atoms has to be specified on the same line. A negative number of atoms stands for all atoms. Example:

3
TYPE1	0.0	0.0	0.0
TYPE2	2	1	4
TYPE3	-1

Note: Indices of dummy atoms always start with total-number-of-atoms plus 1. In the case of a Gromos-QM/MM interface simulations with dummy hydrogen atoms for capping, it is total-number-of-atoms plus number-of-dummy-hydrogens plus 1

EIGENSYSTEM

Section: &RESP

Not documented.

ELECTRON TEMPERATURE

Section: &CPMD

The electronic temperature is read from the next line.
Default is $1000$ K.

ELECTRONIC SPECTRA

Section: &CPMD

Perform a TDDFT calculation [152,153] to determine the electronic spectra. See in section 9.9.1 and under the other keywords for the input sections &LINRES and &TDDFT for further options.

ELECTROSTATIC POTENTIAL [SAMPLE=nrhoout]

Section: &CPMD

Store the electrostatic potential on file. The resulting file is written in platform specific binary format. You can use the cpmd2cube tool to convert it into a Gaussian cube file for visualization. Note that this flag automatically activates the RHOOUT flag as well.

With the optional keyword SAMPLE the file will be written every nrhoout steps during an MD trajectory. The corresponding time step number will be appended to the filepname.

ELF [PARAMETER]

Section: &CPMD

Store the total valence density and the valence electron localization function ELF [154,155,156] on files. The default smoothing parameters for ELF can be changed optionally when specifying in addition the PARAMETER keyword. Then the two parameters ``elfcut'' and ``elfeps'' are read from the next line. The particular form of ELF that is implemented is defined in the header of the subroutine elf.F. Note: it is a very good idea to increase the plane wave cutoff and then specify ``elfcut'' $=0.0$ and ``elfeps'' $=0.0$ if you want to obtain a smooth ELF for a given nuclear configuration. In the case of a spin-polarized (i.e. spin unrestricted) DFT calculation (see keyword LSD) in addition the spin-polarized average of ELF as well as the separate $\alpha$ - and $\beta$ -orbital parts are written to the files LSD_ELF, ELF_ALPHA and ELF_BETA, respectively; see Ref. [157] for definitions and further information. Note: ELF does not make much sense when using Vanderbilt's ultra-soft pseudopotentials!

EMASS

Section: &CPMD

The fictitious electron mass in atomic units is read from the next line.
Default is 400 a.u..

ENERGY PROFILE

Section: &SYSTEM

Perform an energy profile calculation at the end of a wavefunction optimization using the ROKS or ROSS methods.

ENERGYBANDS

Section: &CPMD

Write the band energies (eigenvalues) for k points in the file ENERGYBANDS.

EPR options, see response_p.inc

Section: &RESP

Calculate the EPR $g$ tensor for the system. This routine accepts most, if not all, of the options available in the NMR routine (RESTART, NOSMOOTH, NOVIRTUAL, PSI0, RHO0, OVERLAP and FULL). Most important new options are:
FULL SMART: does a calculation with improved accuracy. A threshold value (between 0 and 1) must be present on the next line. The higher the threshold value, the lower the computational cost, but this will also reduce the accuracy (a bit). Typically, a value of 0.05 should be fine.
OWNOPT: for the calculation of the $g$ tensor, an effective potential is needed. By default, the EPR routine uses the local potential ( $V_{LOC} = V_{PP,LOC} + V_{HARTREE} + V_{XC}$ ). This works well with Goedecker pseudopotentials, but rather poor with Troullier-Martins pseudopotentials. When using this option, the following potential is used instead:

$$V_{EFF} = -\frac{Z}{r}\mathrm{erf}(r/r_c) + V_{HARTREE} + V_{XC}$$

and $r_c$ (greater than 0) is read on the next line.
HYP: calculates the hyperfine tensors. See epr_hyp.F for details.

Contact Reinout.Declerck@UGent.be should you require further information.

EXCHANGE CORRELATION TABLE [NO]

Section: &DFT

Specifies the range and the granularity of the lookup table for the local exchange-correlation energy and potential. The number of table entries and the maximum density have to be given on the next line.
Note that this keyword is only relevant when using OLDCODE and even then it is set to NO be default. Previous default values were 30000 and 2.0.

EXCITED DIPOLE

Section: &PROP

Calculate the difference of dipole moments between the ground state density and a density generated by differently occupied Kohn-Sham orbitals.
On the next line the number of dipole moments to calculate and the total number orbitals has to be given. On the following lines the occupation of the states for each calculation has to be given. By default the dipoles are calculated by the method used for the DIPOLE MOMENT option and the same restrictions apply. If the LOCAL DIPOLE option is specified the dipole moment differences are calculated within the same boxes.

EXTERNAL POTENTIAL {ADD}

Section: &CPMD

Read an external potential from file. With ADD specified, its effects is added to the forces acting on the ions.

EXTERNAL FIELD

Section: &SYSTEM

Applies an external electric field to the system using the Berry phase. The electric field vector in AU is read from the next line.

EXTRAPOLATE WFN {ASPC,POLY} [STORE,CSTEPS=naspc]

Section: &CPMD

Read the number of wavefunctions to retain mextra from the next line.
These wavefunctions are used to extrapolate the initial guess wavefunction in Born-Oppenheimer MD. This can help to speed up BO-MD runs significantly by reducing the number of wavefunction optimization steps needed through two effects: the initial guess wavefunction is much improved and also you do not need to converge as tightly (via setting CONVERGENCE ORBITALS) to conserve energy.

Two extrapolation algorithms are available, the ASPC has shown to yield best energy conservation and is thus the default. The order of the extrapolation is $mextra - 2$ . A simpler polynomial extrapolation POLY is also available. Here the order of the extrapolation is $mextra - 1$ .

With the additional keyword STORE the wavefunction history is also written to restart files. See RESTART for how to read it back.

With the additional keyword CSTEPS=, the number of corrector steps (SCF steps) can be limited to $naspc$ . This feature becomes active as soon as a full wavefunction history exists.

FACMASS

Section: &PIMD

Obtain the fictitious nuclear masses $M_I^\prime$ within path integral molecular dynamics from the real physical atomic masses $M_I$ (as tabulated in the DATA ATWT / .../ statement in atoms.F) by multiplying them with the dimensionless factor WMASS that is read from the following line; if the NORMAL MODES or STAGING propagator is used obtain $M_I^{\prime (s)}=$   WMASS$\cdot M_I^{(s)}$ for all replicas $s=1, \dots , P$ ; see e.g. Ref. [142] eq. (2.37) for nomenclature.
Default value of WMASS is 1.0

FACTOR

Section: &PATH

Step for propagating string (see [128]).
Default value is 1.0

FFTPARM FILE [ON,OFF]

Section: &CPMD

Controls the use of self-adapting features when the compiled in FFT library supports this. When enabled, CPMD will turn on additional runtime optimizations of the FFT library. The resulting parameters will be written to a file called FFTPARM_DATA and re-read on subsequent runs. The parameters in the file are machine specific and when moving a job to a different machine, or using a different FFT library the file should be discarded.

The use of self-adapting runtime optimizations incurs additional overhead and thus does only sometimes lead to faster execution. It is recommended to stick with the default settings unless you know what you are doing.

FILE FUSION

Section: &CPMD

Reads in two separate RESTART files for ground state and ROKS excited state and writes them into a single restart file.
Required to start SURFACE HOPPING calculations.

FILEPATH

Section: &CPMD

The path to the files written by CPMD (RESTART.x, MOVIE, ENERGIES, DENSITY.x etc.) is read from the next line. This overwrites the value given in the environment variable CPMD_FILEPATH. Default is the current directory or ``./''.

FINITE DIFFERENCES

Section: &CPMD

The step length in a finite difference run for vibrational frequencies (VIBRATIONAL ANALYSIS keywords) is read from the next line.
With the keywords COORD=coord_fdiff(1..3) and RADIUS=radius put in the same line as the step length, you can specify a sphere in order to calculate the finite differences only for the atoms inside it. The sphere is centered on the position coord_fdiff(1..3) with a radius radius (useful for a point defect).

NOTE: The the step length for the finite difference is always in Bohr (default is 1.0d-2 a.u.). The (optional) coordinates of the center and the radius are read in either Angstrom or Bohr, depending on whether the ANGSTROM keyword is specified or not.

FIXRHO UPWFN [VECT LOOP WFTOL]

Section: &CPMD

Wavefunctions optimization with the method of direct inversion of the iterative subspace (DIIS), performed without updating the charge density at each step. When the orbital energy gradients are below the given tolerance or when the maximum number of iterations is reached, the KS energies and the occupation numbers are calculated, the density is updated, and a new wavefunction optimization is started. The variations of the density coefficients are used as convergence criterion. The default electron temperature is 1000 K and 4 unoccupied states are added. Implemented also for k-points. Only one sub-option is allowed per line and the respective parameter is read from the next line. The parameters mean:

VECT:

The number of DIIS vectors is read from the next line. (ODIIS with 4 vectors is the default).

LOOP:

the minimum and maximum number of DIIS iterations per each wfn optimization is read from the following line. Default values are 4 and 20.

WFTOL:

The convergence tolerance for the wfn optimization during the ODIIS is read from the following line. The default value is $10^{-7}$ . The program adjusts this criterion automatically, depending on the convergence status of the density. As the density improves (when the density updates become smaller), also the wavefunction convergence criterion is set to its final value.

FORCE FIELD

Section: &CLASSIC

not documented.

FORCE STATE

Section: &TDDFT

The state for which the forces are calculated is read from the next line. Default is for state 1.

FREE ENERGY FUNCTIONAL

Section: &CPMD

Calculates the electronic free energy using free energy density functional [53,54,56,158] from DFT at finite temperature.
This option needs additional keywords (free energy keywords).
By default we use LANCZOS DIAGONALIZATION with Trotter factorization and BOGOLIUBOV CORRECTION. If the number of states is not specified, use $N_{electrons}/2+4$ .

FREEZE QUANTUM

Section: &CLASSIC

Freeze the quantum atoms and performs a classical MD on the others (in QMMM mode only !).

FULL TRAJECTORY

Section: &CLASSIC

Not documented

FUNCTIONAL functionals

Section: &DFT

Single keyword for setting up XC-functionals.
Available functionals are NONE, SONLY, LDA (in PADE form), BONLY, BP, BLYP, XLYP, GGA (=PW91), PBE, PBES, REVPBE, HCTH, OPTX, OLYP, TPSS, PBE0, B1LYP, B3LYP, X3LYP,PBES

FUKUI [N=nf]

Section: &RESP

Calculates the response to a change of occupation number of chosen orbitals. The indices of these orbitals are read from the following nf lines (default nf=1). The orbitals themselves are not read from any RESTART file but from WAVEFUNCTION.* files generated with RHOOUT in the &CPMD section; to recall this the orbital numbers have to be negative, just like for the RHOOUT keyword.

A weight can be associated with each orbital if given just after the orbital number, on the same line. It corresponds to saying how many electrons are put in or taken from the orbital. For example;

   FUKUI N=2
   -i 1.0
   -j -1.0

corresponds to the response to taking one electron from orbital i and put it in orbital j.

GAUGE {PARA,GEN,ALL}

Section: &LINRES

Gauge of the linear-response wavefunctions. Default is the parallel-transport gauge (PARA) for closed-shell calculations and a sensible combination of the parallel-transport gauge and the full-rotation gauge (GEN) for all other cases. The full-rotation gauge can be enforced for all states by selecting ALL. See [127].

GC-CUTOFF

Section: &DFT

On the next line the density cutoff for the calculation of the gradient correction has to be specified. The default value is $10^{-8}$ . Experience showed that for a small CUTOFF value (e.g. when using Vanderbilt pseudopotentials) a bigger values have to be used. A reasonable value for a 25 ryd cutoff calculation is $5 \cdot 10^{-6}$ .
Warning: for the HCTH functional, since it includes both the $xc$ part and the gradient correction in a unique functional, a GC-CUTOFF too high (e.g. $\geq 5 \cdot 10^{-5}$ ) could result in not including any $xc$ part with uncontrolled related consequences.

GDIIS

Section: &CPMD

Use the method of direct inversion in the iterative subspace combined with a quasi-Newton method (using BFGS) for optimization of the ionic positions [159].The number of DIIS vectors is read from the next line.
GDIIS with 5 vectors is the default method in optimization runs.

GENERATE COORDINATES

Section: &ATOMS

The number of generator atoms for each species are read from the next line.
These atoms are used together with the point group information to generate all other atomic positions. The input still has to have entries for all atoms but their coordinates are overwritten. Also the total number of atoms per species has to be correct.

GENERATE REPLICAS

Section: &PIMD

Generate quantum free particle replicas from scratch given a classical input configuration according to the keyword DEBROGLIE specification. This is the default if INITIALIZATION is active.

GRADIENT CORRECTION [functionals]

Section: &DFT

Individual components of gradient corrected functionals can be selected. Rarely needed anymore, use the FUNCTIONAL keyword instead.

Functionals implemented are for the exchange energy:
BECKE88 [137], GGAX [160] PBEX [161], REVPBEX [162], HCTH [163], OPTX [164],PBESX [165]
and for the correlation part:
PERDEW86 [167], LYP [166], GGAC [160], PBEC [161], REVPBEC [162], HCTH [163] OLYP [164],PBESC [165].
Note that for HCTH, exchange and correlation are treated as a unique functional.
The keywords EXCHANGE and CORRELATION can be used for the default functionals (currently BECKE88 and PERDEW86). If no functionals are specified the default functionals for exchange and correlation are used.

GSHELL

Section: &CPMD

Write a file GSHELL with the information on the plane waves for further use in S(q) calculations.

HAMILTONIAN CUTOFF

Section: &CPMD

The lower cutoff for the diagonal approximation to the Kohn-Sham matrix [33] is read from the next line.
Default is 0.5 atomic units.
For variable cell dynamics only the kinetic energy as calculated for the reference cell is used.

HAMILTONIAN CUTOFF

Section: &RESP

The value where the preconditioner (the approximate Greens function $(V_{kin}+V_{coul}-\epsilon_{KS})^{-1})$ is truncated. HTHRS can also be used. Default value is 0.5.

HARDNESS

Section: &RESP

Not documented.

HARMONIC REFERENCE SYSTEM [OFF]

Section: &CPMD

Switches harmonic reference system integration [33] on/off.
The number of shells included in the analytic integration is controlled with the keyword HAMILTONIAN CUTOFF.
By default this option is switched off.

HARTREE-FOCK

Section: &DFT

Do a Hartree-Fock calculation. This only works correctly for isolated systems. It should be used with care, it needs enormous amounts of CPU time.

HARTREE

Section: &DFT

Do a Hartree calculation. Only of use for testing purposes.

HESSCORE

Section: &CPMD

Calculates the partial Hessian after relaxation of the enviroment, equivalent to NSMAXP=0 (PRFO NSMAXP).

HESSIAN [DISCO,SCHLEGEL,UNIT,PARTIAL]

Section: &CPMD

The initial approximate Hessian for a geometry optimization is constructed using empirical rules with the DISCO [168] or Schlegel's [169] parametrization or simply a unit matrix is used.
If the option PARTIAL is used the initial approximate Hessian for a geometry optimization is constructed from a block matrix formed of the parametrized Hessian and the partial Hessian (of the reaction core). If the reaction core spans the entire system, its Hessian is simply copied. The keywords RESTART PHESS are required.

HFX CUTOFF

Section: &SYSTEM

Set an additional cutoff for wavefunction and density to be used in the calculation of exact exchange. Cutoffs for wavefunctions and densities are read from the next line in Rydberg units. Defaults are the same cutoffs as for the normal calculation. Only lower cutoffs than the defaults can be specified.

HTHRS

Section: &LINRES

Threshold for Hessian in preconditioner for linear response optimizations. Default is 0.5.

IMPLICIT NEWTON RAPHSON {PREC, CONTINUE, VERBOSE, ALTERNATIVE, STEP} [N=nreg]

Section: &CPMD

Not documented.

INITIALIZATION

Section: &PIMD

Provide an initial configuration for all replicas as specified either by GENERATE REPLICAS or by READ REPLICAS. This option is automatically activated if RESTART COORDINATES is not specified. It is defaulted to GENERATE REPLICAS together with DEBROGLIE CENTROID and a temperature of 500 Kelvin.

INITIALIZE WAVEFUNCTION [RANDOM, ATOMS]

Section: &CPMD

The initial guess for wavefunction optimization are either random functions or functions derived from the atomic pseudo-wavefunctions.
Default is to use the atomic pseudo-wavefunctions.

INTERACTION

Section: &RESP

Not documented.

INTERFACE {EGO,GMX} [MULLIKEN,LOWDIN,ESP,HIRSHFELD,PCGFIRST]

Section: &CPMD

Use CPMD together with a classical molecular dynamics code. CPMD and the classical MD code are run simultaneously and communicate via a file based protocol. See the file egointer.F for more details. This needs a specially adapted version of the respective classical MD code. So far, there is an interface[170,4] to the MD programs ego[171,172] and Gromacs[133].

When using the suboption PCGFIRST the code will use PCG MINIMIZE on the very first wavefunction optimization and then switch back to DIIS.

INTFILE [READ,WRITE,FILENAME]

Section: &CPMD

This keyword means Interface File and allows to select a special file name in the reading and writing stages. The file name (max 40 characters) must be supplied in the next line.

ISOLATED MOLECULE

Section: &CPMD

Calculate the ionic temperature assuming that the system consists of an isolated molecule or cluster.
Note: This keyword affects exclusively the determination of the number of dynamical degrees of freedom. This keyword does not activate the 'cluster option' SYMMETRY 0, but it is activated if SYMMETRY 0 is used unless the keyword QMMM is set as well. It allows studying an isolated molecule or cluster within periodic boundary conditions.

ISOTOPE

Section: &ATOMS

Changes the default masses of the atoms.
This keyword has to be followed by NSP lines (number of atom types). In each line the new mass (in a.m.u.) of the respective species has to be specified (in order of their definition).

ISOTROPIC CELL

Section: &SYSTEM

Specifies a constraint on the super cell in constant pressure dynamics or geometry optimization. The shape of the cell is held fixed, only the volume changes.

KEEPREALSPACE

Section: &RESP

Like the standard CPMD option, this keeps the C0 ground state wavefunctions in the direct space representation during the calculation. Can save a lot of time, but is incredibly memory intensive.

KOHN-SHAM ENERGIES [OFF,NOWAVEFUNCTION]

Section: &CPMD

Calculation of the Kohn-Sham energies and the corresponding orbitals.
The number of empty states that have to be calculated in addition to the occupied states is read from the next line.
The Kohn-Sham orbitals are stored on the file RESTART.x except if the keyword NOWAVEFUNCTION is used. In this case, the program does not allocate memory for wavefunctions for all k points. It computes eigenvalues k point per k point losing information about wavefunctions. This keyword is used for band structure calculation to compute the eigenvalues for many k points.
Default is not to calculate Kohn-Sham energies (OFF ).
Warning: The usage of this keyword needs special care (especially restarts).

KPERT [MONKHORSTPACK,SCALE]

Section: &RESP

Calculation of total energy and electronic density of states with an arbitrary number of k-points (at almost no additional computational effort). The method is based on a $\mathbf{k}\cdot \mathbf{p}-$ like approximation developed in the framework of the density functional perturbation theory [111]. For a sampling of the BZ determined by the Monkhorst-Pack algorithm, the option MONKHORSTPACK has to be specified, followed by the dimension of the mesh along the 3 reciprocal space axis $(NK_{1} , NK_{2} , NK_{3})$ . If omitted, the individual absolute coordinates of the k-points have to be given one by one in the following lines. The SCALE option allows to specify them in units of the reciprocal cell vectors.

The line after KPERT has to contain the total number of k-points $(NKPTS)$ , which have then to be given by their coordinates and the associated weights $(RK,WK)$ in the format:
$NKPTS$
$RK_{x1} \; RK_{y1} \; RK_{z1} \; WK_{1}$
$\dots$
$RK_{x NKPTS} \; RK_{y NKPTS} \; RK_{z NKPTS} \; WK_{NKPTS}$ .
Three response wavefunctions are calculated, corresponding to the three independent orientations of the k basis vectors in reciprocal space. Therefore, 3 independent optimization loops are started ($x,y$ and $z$ ), and the 3 sets of wfns are stored (you need 4 times the memory required for a standard wavefunction optimization). The second order correction to the $\Gamma$ -point total energy is calculated for the requested k-point mesh.

Further options are (each in a new line of the input file ):

WRITE_C1

the 3 sets of response wfns are stored in three separate restart files.

HAMILTONIAN

the k-dependent Hamiltonian is constructed via the second order perturbation theory approximation, and the corresponding KS energies are calculated. Due to technical reasons, for each k-point $2*NSTATE$ KS energies are calculated, however only those corresponding to occupied orbitals are reliable.

READ_C1

the response wfns are read from RESTART.P_{xyz}.

BUILD_C00

the set of k-dependent wfns (first order correction) is calculated from the unperturbed $\Gamma$ -point wfns together with the response orbitals. They are then written in a standard RESTART file. From this restart file one can perform a calculation of the Hamiltonian matrix for each kpoint and calculate the KS energies (use LANCZOS DIAGO in &CPMD and the KPOINT option ONLYDIAG in &SYSTEM. The k-point mesh must be the same used in the linear response calculation. set also NOSPHERICAL CUTOFF in &SYSTEM).

NORESTART

no RESTART file is written.

KPOINTS options

Section: &SYSTEM

With no option, read in the next line with the number of k-points and for each k-point, read the components in the Cartesian coordinates (units $2\pi/a$ ) and the weight.

MONKHORST-PACK

Read in the next line three numbers for the Monkhorst-Pack mesh. The program calculates then the special k-points. With the keyword SHIFT=kx ky kz in the same line, you can precise the constant vector shift.

SYMMETRIZED

Symmetrized special k-points mesh (useful if you use a constant vector shift).

FULL

Construct full Monkhorst-Pack mesh with only inversion symmetry. Useful for molecular dynamics simulation The keywords SYMMETRIZED FULL preserves all symmetry of Bravais lattice so there is no need to symmetrize density and forces.

SCALED

You can give k-points in reciprocal space coordinates.

BANDS

This option is to calculate the band structure.
For each line you have to specify the number of k-points for the band, the initial and the final k-point. To finish the input, put:
0 0. 0. 0. 0. 0. 0.

BLOCK=n [OPTIONS]

The block option, specifies the number of k-points in the memory. The program uses a swap file to store the wavefunctions only by default. With the following options, you can change this behavior:

ALL

Three swap files are used to store wavefunctions and others arrays related to k-points. Swap files are in the current directory or the temporary directory given by environment variable TMPDIR. The use of memory is smaller than with the above option.

CALCULATED

One swap file is used to store only wavefunctions. The other arrays related to k-points are calculated each time if needed.

NOSWAP

The wavefunctions are not swapped. This is useful to calculate eigenvalues for each k point with little memory used.
Warning: The wavefunctions calculated are irrelevant. You have to specify explicitly some other options to use it:
MAXSTEP 1 and
STORE OFF WAVEFUNCTIONS DENSITY POTENTIAL.

LANCZOS DIAGONALIZATION {ALL}

Section: &CPMD

Use Lanczos diagonalization scheme.
Default with free energy functional.

LANCZOS DIAGONALIZATION {OPT,RESET=n}

Section: &CPMD

Use Lanczos diagonalization scheme after (OPT) or periodically during (RESET=n) direct wavefunction optimization using ODIIS. The number n specifies the number of DIIS resets (ODIIS NO_RESET=nreset) due to poor progress until the wavefunction is diagonalized. This can be helpful if the wavefunction is converging very slowly.

LANCZOS PARAMETER [N=n] [ALL]

Section: &CPMD

Give four parameters for Lanczos diagonalization in the next line:

• Maximal number of Lanczos iterations (50 is enough),
• Maximal number for the Krylov sub-space (8 best value),
• Blocking dimension ( $\leq NSTATE$ , best in range 20-100) If you put a negative or zero number, this parameter is fixed by the program in function of the number of states ( $(n+1)/(int(n/100+1))$ ).
• Tolerance for the accuracy of wavefunctions
  ($10^{-8}$ otherwise $10^{-12}$ with Trotter approximation)

If n is specified, read $n-1$ lines after the first one, containing a threshold density and a tolerance. See the hints section 9.13.1 for more information.

LANCZOS [CONTINUE,DETAILS]

Section: &RESP

lanczos_dim iterations conv_threshold lanczos_dim= dimension of the vibrational d.o.f. iterations = no. of iterations desired for this run conv_threshold = threshold for convergence on eigenvectors CONTINUE = argument for continuing Lanczos diagonalization from a previous run (reads file LANCZOS_CONTINUE) DETAILS = argument for verbosity. prints a lot of stuff

LBFGS [NREM, NTRUST, NRESTT, TRUSTR]

Section: &CPMD

Use the limited-memory BFGS method (L-BFGS) for linear scaling optimization of the ionic positions. For more information, see [146]. The information about the Hessian for the quasi-Newton method employed is derived from the history of the optimization [146,173].
Only one sub-option is allowed per line and the respective parameter is read from the next line. The parameters mean:

NREM:

Number of ionic gradients and displacements remembered to approximate the Hessian. The default is either 40 or the number of ionic degrees of freedom, whichever is smaller. Values greater the number of degrees of freedom are not advisable.

NTRUST:

NTRUST=1 switches from a trust radius algorithm to a line search algorithm. The default value of 0 (trust radius) is recommended.

NRESTT:

NRESTT$>$ 0 demands a periodic reset of the optimizer every NRESTT steps. Default is 0 (no periodic reset). This option makes only sense if the ionic gradient is not accurate.

TRUSTR:

Maximum and initial trust radius. Default is 0.5 atomic units.

It can be useful to combine these keywords with the keywords PRFO, CONVERGENCE ADAPT, RESTART LSSTAT, PRINT LSCAL ON and others.

LDA CORRELATION [functional]

Section: &DFT

The LDA correlation functional is specified.
Possible functionals are NO (no correlation functional), PZ [174], VWN [175], LYP [166] and PW [176].
Default is the PZ, the Perdew and Zunger fit to the data of Ceperley and Alder [177].

LDOS

Section: &PROP

Calculate the layer projected density of states. The number of layers is read from the next line.

To use the LDOS keyword, the user must first have performed a wavefunction optimization and then restart with the PROPERTIES and LANCZOS DIAGONALIZATION keywords in the &CPMD section (and LDOS in the &PROP section).

Warning: If you use special k-points for a special structure you need to symmetrize charge density for which you must specify the POINT GROUP.

LINEAR RESPONSE

Section: &CPMD

A perturbation theory calculation is done, according to the (required) further input in the &RESP section. In the latter, one of the possible perturbation types (PHONONS, LANCZOS, RAMAN, FUKUI, KPERT, NMR, EPR, and others see section 9.10.2) can be chosen, accompanied by further options.

LOCAL DIPOLE

Section: &PROP

Calculate $numloc$ local dipole moments.
$numloc$ is read from the next line followed by two numloc lines with the format:
$xmin$ $ymin$ $zmin$
$xmax$ $ymax$ $zmax$

LOCALIZATION

Section: &TDDFT

Use localized orbitals in the TDDFT calculation. Default is to use canonical orbitals.

LOCALIZE

Section: &HARDNESS

Use localized orbitals in an orbital hardness calculation

LOCALIZE

Section: &PROP

Localize the molecular orbitals as defined through the atomic basis set.
The same localization transformation is then applied also to the wavefunctions in the plane wave basis. These wavefunction can be printed with the keyword RHOOUT specified in the &CPMD section.

LR KERNEL functional

Section: &DFT

Use another functional for the linear response kernel.

LR-TDDFT

Section: &TDDFT

Use full linear response version of TDDFT. Default is to use TAMM-DANCOFF approximation.

LSD

Section: &CPMD

Use the local spin density approximation.
Warning: Not all functionals are implemented for this option.

LOCAL SPIN DENSITY

Section: &CPMD

Use the local spin density approximation.
Warning: Not all functionals are implemented for this option.

LOW SPIN EXCITATION [ROKS,ROSS,ROOTHAAN,CAS22]

Section: &SYSTEM

Use the low spin excited state functional [125]. For ROKS calculations, see also the ROKS keyword in the &CPMD section.

LOW SPIN EXCITATION LSETS

Section: &SYSTEM

Slater transition-state density with restricted open-shell Kohn-Sham (low spin excited state). Currently works only with ROKS but not with ROSS, ROOTHAAN, or CAS22. See Ref. [127].

LSE PARAMETERS

Section: &SYSTEM

Determines the energy expression used in LSE calculations. The two parameters LSEA and LSEB are read from the next line.

$$E =$$   LSEA$$\cdot E(Mixed) +$$   LSEB$$\cdot E(Triplet)$$

The default (LSEA $= 2$ and LSEB $= 1$ ) corresponds to singlet symmetry. For the lowest triplet state, the LSE PARAMETERS must be set to 0 and 1 (zero times mixed state plus triplet). See ref [125] for a description of the method.

MAXCPUTIME

Section: &CPMD

The maximum CPU TIME in seconds to be used is read from the next line. The calculation will stop after the given amount of time.
Default is no limit.

MAXITER

Section: &CPMD

The maximum number of iteration steps for the self-consistency of wavefunctions. Recommended use instead of MAXSTEP for pure wavefunction optimization. The value is read from the next line.
Default is 10000 steps.

MAXSTEP

Section: &CPMD

The maximum number of steps for geometry optimization or molecular dynamics to be performed. In the case of pure wavefunction optimization, this keyword may be used instead of MAXITER. The value is read from the next line.
Default is 10000 steps.

MAXSTEP

Section: &LINRES

Maximum number of optimization steps for linear response optimizations. Default is 1000.

MEMORY {SMALL, BIG}

Section: &CPMD

Using BIG, the structure factors for the density cutoff are only calculated once and stored for reuse.
This option allows for considerable time savings in connection with Vanderbilt pseudopotentials.
Default is (SMALL) to recalculate them whenever needed.

MESH

Section: &SYSTEM

The number of real space mesh points in $x-$ , $y-$ and $z-$ direction is read from the next line.
If the values provided by the user are not compatible with the plane-wave cutoff or the requirements of the FFT routines the program chooses the next bigger valid numbers.
Default are the minimal values compatible with the energy cutoff and the FFT requirements.

METADYNAMICS

Section: &ATOMS

Initiate Metadynamics (see section 9.11 for more information on the available options and the input format). This section of the input has to be terminated by a line containing END METADYNAMICS.

MIRROR

Section: &CPMD

Write the input file to the output.

MIXDIIS

Section: &CPMD

Not documented

MIXSD

Section: &CPMD

Not documented

MODIFIED GOEDECKER [PARAMETERS]

Section: &CPMD

To be used in combination with LOW SPIN EXCITATION ROKS.
Calculation of the off-diagonal Kohn-Sham matrix elements $F_{AB}$ and $F_{BA}$ (with A, B: ROKS-SOMOs) is performed according to a modified Goedecker-Umrigar scheme ( $F_{AB} := (1-\lambda _{AB})F_{AB} + \lambda _{AB} F_{BA}$ and $F_{BA} := (1-\lambda _{BA})F_{BA} + \lambda _{BA} F_{AB}$ ). Default values are $\lambda _{AB}=-0.5$ and $\lambda _{BA}=0.5$ . see Ref. [9].

With the optional keyword PARAMETERS: $\lambda _{AB}$ and $\lambda _{BA}$ are read from the next line. Can be used to avoid unphysical rotation of the SOMOs. Always check the orbitals!

See also 9.12.

MOLECULAR DYNAMICS [CP, BO, PT, CLASSICAL, FILE [XYZ, NSKIP=N, NSAMPLE=M]]

Section: &CPMD

Perform a molecular dynamics (MD) run. CP stands for a Car-Parrinello type MD. With the option BO a Born-Oppenheimer MD is performed where the wavefunction is reconverged after each MD-step. CLASSICAL means that a MD that includes classical atoms is performed.

If FILE is set, then the trajectory is reread from a file instead of being calculated. This is useful for performing analysis on a previous trajectory. Can be used in conjunction with the standard MD options like DIPOLE DYNAMICS and WANNIER; some other features like LINEAR RESPONSE are also enabled. The trajectory is read from a file named TRAJSAVED (usually a copy of a previous TRAJECTORY file), or TRAJSAVED.xyz if XYZ is set. NSKIP and NSAMPLE control the selection of frames read: the frame read at step ISTEP is NSKIP+ISTEP*NSAMPLE.

Default is CP.

MOLECULAR STATES

Section: &TDDFT

Calculate and group Kohn-Sham orbitals into molecular states for a TDDFT calculation.

MOVERHO

Section: &CPMD

Mixing used during optimization of geometry or molecular dynamics. Use atomic or pseudowavefunctions to project wavefunctions in order to calculate the new ones with movement of atoms. Read in the next line the parameter (typically 0.2).

MOVIE TYPE

Section: &ATOMS

Assign special movie atom types to the species.
The types are read from the next line. Values from 0 to 5 were allowed in the original MOVIE format.

MOVIE [OFF, SAMPLE]

Section: &CPMD

Write the atomic coordinates without applying periodic boundary conditions in MOVIE format every IMOVIE time steps on file MOVIE. IMOVIE is read from the next line.
Default is not to write a movie file.

MULTIPLICITY

Section: &SYSTEM

This keyword only applies to LSD calculations.
The multiplicity (2$S$ +1) is read from the next line.
Default is the smallest possible multiplicity.

NEQUI

Section: &PATH

Number of equilibration steps discarded to calculate the mean force.

NEWCODE

Section: &DFT

Switch to select one out of two versions of code to calculate exchange-correlation functionals.
NEWCODE is the default, but not all functionals are available with NEWCODE, if you select one of these, OLDCODE is used automatically. NEWCODE is highly recommended for all new projects and especially for vector computers, also some of the newer functionality is untested or non-functional with OLDCODE.

NLOOP

Section: &PATH

Maximum number of string searches for Mean Free Energy Path searches.

NMR options, see response_p.inc

Section: &RESP

Calculate the NMR chemical shielding tensors for the system. Most important option: FULL, does a calculation with improved accuracy for periodic systems but takes a lot of time. Isolated systems: Use OVERLAP and 0.1 (on next line) for the same effect. Be careful for non-hydrogen nuclei. The shielding is calculated without contribution from the core electrons. Contact sebastia@mpip-mainz.mpg.de for further details.

NOGEOCHECK

Section: &CPMD

Default is to check all atomic distances and stop the program if the smallest distance is below 0.5 Bohr. This keyword requests not to perform the check.

NONORTHOGONAL ORBITALS [OFF]

Section: &CPMD

Use the norm constraint method [178] for molecular dynamics or nonorthogonal orbitals in an optimization run.
On the next line the limit of the off diagonal elements of the overlap matrix is defined. Warning: Adding or deleting this option during a MD run needs special care.

NOOPT

Section: &RESP

Do not perform a ground state wfn optimization. Be sure the restarted wfn is at the BO-surface.

NOPRINT ORBITALS

Section: &PROP

Do not print the wavefunctions in the atomic basis set.

NORMAL MODES

Section: &PIMD

Use the normal mode representation [151] of the path integral propagator. It is possible to impose a mass disparity between centroid and non-centroid coordinates by dividing the fictitious masses of only the non-centroid $s=2, \dots ,P$ replicas by the adiabaticity control factor FACSTAGE. This dimensionless factor must always be specified in the following line. Note: the eigen-frequencies of the $s>1$ replicas are changed by only $\sqrt{\mbox{FACSTAGE}}$ , see Ref. [141](b). Using FACSTAGE $\not= 1.0$ makes only sense in conjunction with CENTROID DYNAMICS where WMASS=1.0 has to be used as well.

NOSE PARAMETERS

Section: &CPMD

The parameters controlling the Nosé thermostats are read in the following order from the next line:
The length of the Nosé-Hoover chain for the ions,
the length of the Nosé-Hoover chain for the electrons,
the length of the Nosé-Hoover chain for the cell parameters.
(The respective default values are 4.)
The multiplication factor (NEDOF0, a real number) for the number of electronic degrees of freedom. The used degrees of freedom (NEDOF) are defined as $NEDOF=NEDOF0*X$ If NEDOF0 is a negative number X is the true number of DOFs, if it's a positive number, X is the number of electronic states (default for NEDOF0 is 6).
The order of the Suzuki/Yoshida integrator (default is 7, choices are 3, 5, 7, 9, 15, 25, 125 and 625),
and the decomposition ratio of the time step (default is 1).
If this keyword is omitted, the defaults are used.
If the keyword is used all parameters have to be specified.

NOSE {IONS, ELECTRONS, CELL} [ULTRA,MASSIVE,CAFES,LOCAL] [T0]

Section: &CPMD

Nosé-Hoover chains [26,27] for the ions, electrons, or cell parameters are used.
The target temperature in Kelvin and the thermostat frequency in $cm^{-1}$ , respectively the fictitious kinetic energy in atomic units and the thermostat frequency in $cm^{-1}$ are read from the next line. For the ionic case the additional keyword ULTRA selects a thermostat for each species, the keyword MASSIVE selects a thermostat for each degree of freedom, and the keyword CAFES can be used to give different temperatures to different groups of atoms[179].

The syntax in the CAFES case is:


NOSE IONS CAFES
    ncafesgrp
  cpnumber_a_1  cpnumber_a_2  Temperature Frequency
...
  cpnumber_n_1  cpnumber_n_2  Temperature Frequency


There are ncafesgrp groups, specified by giving their first CPMD atom number (cpnumber_X_1) and last CPMD atom number (cpnumber_X_2). In the case of hybrid QM/MM simulations, you have to consult the QMMM_ORDER file to find those numbers. The temperature and frequency can be different for each group. All atoms of the system have to be in a CAFES group. A new file, CAFES is created containing the temperature of each group (cols. 2 ...ncafesgrp+1) and the energy of the Nosé-Hoover chains of that group (last columns).

Using CAFES with different temperatures only makes sense if the different groups are decoupled from each other by increasing the masses of the involved atoms. The mass can be specified in the topology / or with the ISOTOPE keyword. However, you can only change the mass of a complete CPMD species at a time. Hence, the topology and/or the input should be such that atoms of different CAFES group are in different species.
NOTE: CAFES is currently not restartable.

The keyword LOCAL collects groups of atoms to separate thermostats, each having its own Nosé-Hoover chain. Specify the local thermostats as follows:

$n_l$ (number of local thermostats)
temperature 1	frequency 1
&vellip#vdots;
temperature $n_l$	frequency $n_l$
$n_r$ (number of atom ranges)
thermostat number	start atom	end atom
&vellip#vdots;	($n_r$ entries)

The parser for the atom ranges uses either the CPMD ordering or the GROMOS ordering in case of classical or QM/MM runs. Multiple ranges may be specified for the same thermostat. Atoms belonging to the same CPMD constraint or the same solvent molecule in QM/MM runs must belong to the same local thermostat.

If T0 option is present, the initial temperature for the Nosé-Hoover chains are read directly after the thermostat frequencies in the same line (also for the LOCAL thermostat). By default it is same as the target temperature of the thermostat. Note: This is not implemented for the CAFES thermostat.

NPREVIOUS

Section: &PATH

String index to restart from. Note that this is just for numbering files, the initial path in collective variables for the search is always string.inp.

NSUP

Section: &SYSTEM

The number of states of the same spin as the first state is read from the next line.
This keyword makes only sense in spin-polarized calculations (keyword LSD).

OACP [DENSITY,REF_DENSITY,FORCE]

Section: &RESP

Not documented

OCCUPATION [FIXED]

Section: &SYSTEM

The occupation numbers are read from the next line.
This keyword must be preceeded by STATES. The FIXED option fixes the occupation numbers for the diagonalization scheme, otherwise this option is meaningless.

ODIIS [NOPRECONDITIONING,NO_RESET=nreset]

Section: &CPMD

Use the method of direct inversion in the iterative subspace for optimization of the wavefunction [180].
The number of DIIS vectors is read from the next line.
(ODIIS with 10 vectors is the default method in optimization runs.)
The preconditioning is controlled by the keyword HAMILTONIAN CUTOFF. Optionally preconditioning can be disabled.
By default, the number of wavefunction optimization cycles until DIIS is reset on poor progress, is the number of DIIS vectors. With ODIIS NO_RESET, this number can be changed, or DIIS resets can be disabled altogether with a value of -1.

OLDCODE

Section: &DFT

see NEWCODE

OPTIMIZE GEOMETRY [XYZ, SAMPLE]

Section: &CPMD

This option causes the program to optimize the geometry of the system through a sequence of wavefunction optimizations and position updates. The additional keyword XYZ requests writing the ``trajectory'' of the geometry additionally in xmol/xyz-format in a file GEO_OPT.xyz. If the keyword SAMPLE is given, NGXYZ is read from the next line, and then only every NGXTZ step is written to the xmol/xyz file. The default is to write every step (NGXYZ = $1$ ).
By default the a BFGS/DIIS algorithm is used (see GDIIS) to updated the ionic positions. Other options are: LBFGS, PRFO, and STEEPEST DESCENT IONS. See OPTIMIZE WAVEFUNCTION for details on the corresponding options for wavefunction optimizations.

OPTIMIZE SLATER EXPONENTS

Section: &PROP

Not documented

OPTIMIZE WAVEFUNCTION

Section: &CPMD

Request a single point energy calculation through a wavefunction optimization. The resulting total energy is printed (for more output options see, e.g.,: PRINT, RHOOUT, ELF) and a RESTART file is written. This restart file is a prerequisite for many other subsequent calculation types in CPMD, e.g. MOLECULAR DYNAMICS CP or PROPERTIES. By default a DIIS optimizer is used (see ODIIS), but other options are: PCG (optionally with MINIMIZE), LANCZOS DIAGONALIZATION, DAVIDSON DIAGONALIZATION, and STEEPEST DESCENT ELECTRONS.

OPTIMIZER [SD,DIIS,PCG,AUTO]

Section: &LINRES

Optimizer to be used for linear response equations. Default is ``AUTO'' which will first use PCG, then switch to DIIS and finally switch to DIIS with full storage and state dependent preconditioner. THAUTO sets the two tolerances for when to do the switch.

ORBITAL HARDNESS [LR,FD]

Section: &CPMD

Perform an orbital hardness calculation. See section &HARDNESS for further input options.

ORBITALS

Section: &HARDNESS

Specify the number of orbitals to be used in a hardness calculation on the next line.

ORTHOGONALIZATION {LOWDIN, GRAM-SCHMIDT}

Section: &CPMD

Orthogonalization in optimization runs is done either by a Löwdin (symmetric) or Gram-Schmidt procedure.
Default is Gram-Schmidt except for parallel runs where Löwdin orthogonalization is used with the conjugate-gradient scheme.

OUTPUT [ALL, GROUPS, PARENT]

Section: &PIMD

Output files for each processor, processor group, or only grandparent. Default is PARENT to standard output file (Note: some information such as messages for correct reading / writing of restart files is lost); GROUPS and ALL write to the files OUTPUT_$n$ where $n$ is the group and bead number, respectively.

OUTPUT [ALL, GROUPS, PARENT]

Section: &PATH

Idem as above, here for Mean Free Energy Path runs.

PARRINELLO-RAHMAN {NPT,SHOCK}

Section: &CPMD

To be used together with MOLECULAR DYNAMICS.
A variable cell MD with the Parrinello-Rahman Lagrangian is performed [29]. With the additional keyword a const NPT MD using the method of Martyna, Tobias, and Klein [31]. With the additional keyword SHOCK a MD simulation using the multiscale shock method [8] is performed.

A few comments on the shock method:
The cell fictitious mass (CMASS) has to be very high or the cell fluctuates too rapidly and the shock compression doesn't work (e.g. 3500000 for a bulk 32 water system which is over 5000 times the typical value). The shock compression simulation technique is an extended Lagrangian not that dissimilar from the Anderson barostat (NpH). Basically, the Lagrangian restricts the simulation so that the shock Hugoniot (Energy vs. pressure and volume) relation is conserved, and so the simulation only visits thermodynamic states induced by the shock (called the Rayleigh line, which relates the pressure to the shock velocity and volume). These two relations, the Hugoniot and the Rayleigh line, describe a steady planar shock. The user has to input a cell mass (CMASS), SHOCK VELOCITY, and initial PRESSURE of the system. For water, the simulation cell will fluctuate for a bit, and then compress fairly rapidly to a final state at significantly higher density and pressure.

PATH INTEGRAL

Section: &CPMD

Perform a path integral molecular dynamics calculation [181,182].
This keyword requires further input in the &PIMD section.

PATH MINIMIZATION

Section: &CPMD

Perform a mean free energy path search [128].
This keyword requires further input in the &PATH section.

PATH SAMPLING

Section: &CPMD

Use CPMD together with a reaction path sampling [183] program. This needs special software. Note: this keyword has nothing to do with path integral MD as activated by the keyword PATH INTEGRAL and as specified in the &PIMD section.

PCG PARAMETER

Section: &TDDFT

The parameters for the PCG diagonalization are read from the next line. If MINIMIZE was used in the DIAGONALIZER then the total number of steps (default 100) and the convergence criteria (default $10^{-8}$ ) are read from the next line. Without minimization in addition the step length (default 0.5) has also to be given.

PCG [MINIMIZE,NOPRECONDITIONING]

Section: &CPMD

Use the method of preconditioned conjugate gradients for optimization of the wavefunction.
The fixed step length is controlled by the keywords TIMESTEP ELECTRONS and EMASS.
If the additional option MINIMIZE is chosen, then additionally line searches are performed to improve the preconditioning.
The preconditioning is controlled by the keyword HAMILTONIAN CUTOFF. Optionally preconditioning can be disabled.

PHONON

Section: &RESP

Calculate the harmonic frequencies from perturbation theory.

POINT GROUP [MOLECULE], [AUTO], [DELTA=delta]

Section: &SYSTEM

The point group symmetry of the system can be specified in the next line. With the keyword AUTO in the next line, the space group is determined automatically. This affects the calculation of nuclear forces and ionic positions. The electronic density and nuclear forces are symmetrized in function of point group symmetry. The group number is read from the next line.
Crystal symmetry groups:

               1  1 (c1)     9   3m (c3v)   17 4/mmm (d4h)   25  222 (d2)
               2 <1>(ci)    10  <3>m(d3d)   18   6   (c6)    26  mm2 (c2v)
               3  2 (c2)    11   4  (c4)    19  <6>  (c3h)   27  mmm (d2h)
               4  m (c1h)   12  <4> (s4)    20   6/m (c6h)   28  23  (t)
               5 2/m(c2h)   13  4/m (c4h)   21   622 (d6)    29  m3  (th)
               6  3 (c3)    14  422 (d4)    22   6mm (c6v)   30  432 (o)
               7 <3>(c3i)   15  4mm (c4v)   23  <6>m2(d3h)   31 <4>3m(td)
               8 32 (d3)    16 <4>2m(d2d)   24  6/mmm(d6h)   32  m3m (oh)

You can specify the point group by its name using the keyword NAME= followed by the name of the point group (one of both notations).
For molecular point groups the additional keyword MOLECULE has to be specified. The Schönflies symbol of the group is read in the following format from the next line:
Group symbol; order of principle axis

Possible group symbols are any Schönflies symbol with the axis number replaced by $n$ (e.g. DNH). For molecular point groups a special orientation is assumed. The principle axis is along $z$ and vertical symmetry planes are orthogonal to $x$ .
DELTA= specifies the required accuracy (default=$10^{-6}$ ).
With the keyword AUTO, the point group is determined automatically.

POISSON SOLVER {HOCKNEY, TUCKERMAN, MORTENSEN} [PARAMETER]

Section: &SYSTEM

This keyword determines the method for the solution of the Poisson equation for isolated systems. Either Hockney's method [72] or Martyna and Tuckerman's method [75] is used. The smoothing parameter (for Hockney's method) or $L \times \alpha$ for Tuckerman's method can be read from the next line using the PARAMETER keyword.

For more information about the usage of this parameter see also section 9.4.

POLAK

Section: &RESP

Uses the Polak-Ribiere formula for the conjugate gradient algorithm. Can be safer in the convergence.

POLARISABILITY

Section: &PROP

Computes the polarizability of a system, intended as dipole moment per unit volume.

POLYMER

Section: &SYSTEM

Assume periodic boundary condition in $x$ -direction.

POPULATION ANALYSIS [MULLIKEN, DAVIDSON],[n-CENTER]

Section: &PROP

The type of population analysis that is performed with the projected wavefunctions.
Löwdin charges are given with both options. For the Davidson analysis [184] the maximum complexity can be specified with the keyword n-CENTER.
Default for n is 2, terms up to 4 are programmed. For the Davidson option one has to specify the number of atomic orbitals that are used in the analysis. For each species one has to give this number in a separate line. An input example for a water molecule is given in the hints section 9.14.

PRESSURE

Section: &SYSTEM

The external pressure on the system is read from the next line (in kbar).

PRFO [MODE, MDLOCK, TRUSTP, OMIN, PRJHES, DISPLACEMENT, HESSTYPE]

Section: &CPMD

Use the partitioned rational function optimizer (P-RFO) with a quasi-Newton method for optimization of the ionic positions. For more information, see [146]. The approximated Hessian is updated using the Powell method [185]. This method is used to find transition states by following eigenmodes of the approximated Hessian [191,146].

Only one suboption is allowed per line and the respective parameter is read from the next line. The suboption PRJHES does not take any parameter. If it is present, the translational and rotational modes are removed from the Hessian. This is only meaningful for conventional (not microiterative) transition state search. The parameters mean:

MODE:

Number of the initial Hessian eigenmode to be followed. Default is 1 (lowest eigenvalue).

MDLOCK:

MDLOCK=1 switches from a mode following algorithm to a fixed eigenvector to be maximized. The default value of 0 (mode following) is recommended.

TRUSTP:

Maximum and initial trust radius. Default is 0.2 atomic units.

OMIN:

This parameter is the minimum overlap between the maximized mode of the previous step and the most overlapping eigenvector of the current Hessian. The trust radius is reduced until this requirement is fulfilled. The default is 0.5.

DISPLACEMENT:

Finite-difference displacement for initial partial Hessian. The default is 0.02.

HESSTYPE:

Type of initial partial Hessian. 0: Finite-difference. 1: Taken from the full Hessian assuming a block-diagonal form. See keyword HESSIAN. The default is 0.

It can be useful to combine these keywords with the keywords CONVERGENCE ENERGY, RESTART LSSTAT, RESTART PHESS, PRFO NSVIB, PRINT LSCAL ON and others.

PRFO [NVAR, CORE, TOLENV, NSMAXP]

Section: &CPMD

If any of these suboptions is present, the microiterative transition state search scheme for optimization of the ionic positions is used. For more information, see [146]. A combination of the L-BFGS and P-RFO methods is employed for linear scaling search for transition states [146,186]. Before each P-RFO step in the reaction core towards the transition state, the environment is fully relaxed using L-BFGS.
Only one suboption is allowed per line. The reaction core can be selected using the NVAR or CORE=ncore suboptions. The value in the line after PRFO NVAR sets the number of ionic degrees of freedom in the reaction core. The ncore values following the line PRFO CORE=ncore select the member atoms of the reaction core. If unspecified, the NVAR/3 first atoms form the reaction core.

The parameters read with the two remaining suboptions are:

TOLENV:

Convergence criterion for the maximum component of the gradient acting on the ions of the environment until a P-RFO step within the reaction core is performed. Default is one third of the convergence criterion for the gradient of the ions (CONVERGENCE GEOMETRY).

NSMAXP:

Maximum number of P-RFO steps to be performed in the reaction core. The keyword HESSCORE corresponds to PRFO NSMAXP with NSMAXP=0.

It can be useful to combine these keywords with the keywords LBFGS, CONVERGENCE ADAPT, CONVERGENCE ENERGY, RESTART LSSTAT, RESTART PHESS, PRFO NSVIB, PRINTLSCAL ON, the other suboptions of PRFO, and others.

PRFO NSVIB

Section: &CPMD

Perform a vibrational analysis every NSVIB P-RFO steps on the fly. This option only works with the P-RFO and microiterative transition state search algorithms. In case of microiterative TS search, only the reaction core is analyzed.

PRINT COORDINATES

Section: &CLASSIC

Not documented

PRINT ENERGY {ON, OFF} [EKIN, ELECTROSTATIC, ESR, ESELF, EFREE, EBAND, ENTROPY, EPSEU, EHEP, EHEE, EHII, ENL, EXC, VXC, EGC, EBOGO]

Section: &CPMD

Display or not information about energies.

PRINT FF

Section: &CLASSIC

Not documented

PRINT LEVEL

Section: &PIMD

The detail of printing information is read as an integer number from the next line. Currently there is only minimal output for $<5$ and maximal output for $\geq 5$ .

PRINT LEVEL

Section: &PATH

Idem as above, here for Mean Free Energy Path searches.

PRINT {ON,OFF} [INFO, EIGENVALUES, COORDINATES, LSCAL, FORCES, WANNIER]

Section: &CPMD

A detailed output is printed every IPRINT iterations. Either only different contribution to the energy or in addition the atomic coordinates and the forces are printed. IPRINT is read from the next line if the keywords ON or OFF are not specified.
Default is only energies after the first step and at the end of the run. OFF switches the output off.

PROCESSOR GROUPS

Section: &PIMD

This is only needed for fine-tuning load balancing in case of path integral runs iff two level parallelization is used. The default optimizes the combined load balancing of the parallelization over replicas and g-vectors. The default load distribution is usually optimal. Separate the total number of processors into a certain number of processor groups that is read from the following line; only 2$^N$ = 2, 4, 8, 16, $\dots$ groups are allowed and the maximum number of groups is the number of replicas. Every processor group is headed by one PARENT and has several CHILDREN that work together on a single replica at one time; the processor groups work sequentially on replicas if there is more than one replica assigned to one processor group. Note: if the resulting number of processor groups is much smaller than the number of replicas (which occurs in ``odd'' cases) specifying the number of processor groups to be equal to the number of replicas might be more efficient. This keyword is only active in parallel mode.

PROCESSOR GROUPS

Section: &PATH

Idem as above, here for mean free energy path search.

PROJECT WAVEFUNCTION

Section: &PROP

The wavefunctions are projected on atomic orbitals.
The projected wavefunctions are then used to calculate atomic populations and bond orders. The atomic orbitals to project on are taken from the &BASIS section. If there is no &BASIS section in the input a minimal Slater basis is used. See section 11.5.3 for more details.

PROJECT [NONE, DIAGONAL, FULL]

Section: &CPMD

This keyword is controlling the calculation of the constraint force in optimization runs.

PROPERTIES

Section: &CPMD

Calculate some properties.
This keyword requires further input in the &PROP section.

PROPERTY { STATE }

Section: &TDDFT

Calculate properties of excited states at the end of an ELECTRONIC SPECTRA calculations. default is to calculate properties for all states. Adding the keyword STATE allows to restrict the calculation to only one state. The number of the state is read from the next line.

QMMM [QMMMEASY]

Section: &CPMD

Activate the hybrid QM/MM code. This keyword requires further input in the section &QMMM.

The QM driver is the standard CPMD. An interface program (MM_Interface) and a classic force field (Gromos[129]/Amber[131]-like) are needed to run the code in hybrid mode[130,187,188,189,190]. This code requires a special license and is not included in the standard CPMD code. (see section 9.16 for more information on the available options and the input format).

QS_LIMIT

Section: &LINRES

Tolerance above which we use quadratic search algorithm in linear response calculations.

QUENCH [IONS, ELECTRONS, CELL, BO]

Section: &CPMD

The velocities of the ions, wavefunctions or the cell are set to zero at the beginning of a run.
With the option BO the wavefunctions are converged at the beginning of the MD run.

RAMAN

Section: &RESP

Calculate the polarizability (also in periodic systems) as well as Born-charges and dipole moment.

RANDOMIZE [COORDINATES, WAVEFUNCTION, DENSITY, CELL]

Section: &CPMD

The ionic positions or the wavefunction or the cell parameters are randomly displaced at the beginning of a run.
The maximal amplitude of the displacement is read from the next line.

RANDOMIZE

Section: &TDDFT

Randomize the initial vectors for the diagonalization in a TDDFT calculation. The amplitude is read from the next line. Default is not to randomize the vectors.

RATTLE

Section: &CPMD

This option can be used to set the maximum number of iterations and the tolerance for the iterative orthogonalization. These two numbers are read from the next line.
Defaults are 30 and $10^{-6}$ .

READ REPLICAS

Section: &PIMD

Read all $P$ replicas from a file with a name to be specified in the following line, for the input format see subroutine rreadf.F.

REAL SPACE WFN KEEP [SIZE]

Section: &CPMD

The real space wavefunctions are kept in memory for later reuse. This minimizes the number of Fourier transforms and can result in a significant speedup at the expense of a larger memory use. With the option SIZE the maximum available memory for the storage of wavefunctions is read from the next line (in MBytes). The program stores as many wavefunctions as possible within the given memory allocation.

REFATOM

Section: &HARDNESS

Specify the reference atom to be used in a hardness calculation on the next line. This option is to be used together with the ORBITALS and LOCALIZE.

REFERENCE CELL [ABSOLUTE, DEGREE, VECTORS]

Section: &SYSTEM

This cell is used to calculate the Miller indices in a constant pressure simulation. This keyword is only active together with the option PARRINELLO-RAHMAN.
The parameters specifying the reference (super) cell are read from the next line.
Six numbers in the following order have to be provided: $a$ , $b/a$ , $c/a$ , $\cos \alpha$ , $\cos \beta$ , $\cos \gamma$ .
The keywords ABSOLUTE and DEGREE are described in CELL option.

REFUNCT functionals

Section: &DFT

Use a special reference functional in a calculation. This option is not active.

REORDER LOCAL

Section: &TDDFT

Reorder the localized states according to a distance criteria. The number of reference atoms is read from the next line. On the following line the position of the reference atoms within the set of all atoms has to be given. The keyword LOCALIZE is automatically set. The minimum distance of the center of charge of each state to the reference atoms is calculated and the states are ordered with respect to decreasing distance. Together with the SUBSPACE option in a TAMM-DANCOFF calculation this can be used to select specific states for a calculation.

REORDER

Section: &TDDFT

Reorder the canonical Kohn-Sham orbitals prior to a TDDFT calculation. The number of states to be reordered is read from the next line. On the following line the final rank of each states has to be given. The first number given corresponds to the HOMO, the next to the HOMO - 1 and so on. All states down to the last one changed have to be specified, no holes are allowed. This keyword can be used together with the SUBSPACE option in a TAMM-DANCOFF calculation to select arbitrary states. Default is to use the ordering of states according to the Kohn-Sham eigenvalues.

REPLICA NUMBER

Section: &PATH

Number of replicas along the string.

RESCALE OLD VELOCITIES

Section: &CPMD

Rescale ionic velocities after RESTART to the temperature specified by either TEMPERATURE, TEMPCONTROL IONS, or NOSE IONS. Useful if the type of ionic thermostatting is changed, (do not use RESTART NOSEP in this case).
Note only for path integral runs: the scaling is only applied to the first (centroid) replica.

RESTART [OPTIONS]

Section: &CPMD

This keyword controls what data is read (at the beginning) from the file RESTART.x.
Warning: You can only read data that has been previously written into the RESTART-file.
A list of different OPTIONS can be specified. List of valid options:

WAVEFUNCTION

Read old wavefunction from restart file.

OCCUPATION

Read old occupation numbers (useful for free energy functional.

COORDINATES

Read old coordinates from restart file.

VELOCITIES

Read old ionic, wavefunction and (cell) velocities from restart file.

CELL

Read old cell parameters from restart file.

GEOFILE

Read old ionic positions and velocities from file GEOMETRY. This file is updated every time step. It has higher priority than the COORDINATES option.

NORESTART

Do not open a restart file at all. Useful in combination with GEOFILE to restart from coordinates and velocities without having to copy them into the input.

ACCUMULATORS

Read old accumulator values, for example the time step number, from restart file.

HESSIAN

Read old approximate Hessian from file HESSIAN.

NOSEE

Restart Nosé thermostats for electrons with values stored on restart file.

NOSEP

Restart Nosé thermostats for ions with values stored on
restart file.

NOSEC

Restart Nosé thermostats for cell parameters with values stored on restart file.

LATEST

Restart from the latest restart file as indicated in file LATEST.

PHESS

Read partial Hessian (Hessian of the reaction core) for transition state search or vibrational analysis from restart file. Useful with the keywords PRFO or HESSIAN [DISCO,SCHLEGEL,UNIT] PARTIAL.

LSSTAT

Read all status information of the linear scaling optimizers (L-BFGS and P-RFO) including L-BFGS history but excluding partial Hessian for P-RFO from restart file. The partial Hessian is read separately using RESTART PHESS. Useful with the keywords LBFGS and/or PRFO.

ADPTTL

Read wavefunction convergence criteria at the current point of geometry optimization from restart file. Useful with the keywords CONVERGENCE [ADAPT, ENERGY, CALFOR].

VIBANALYSIS

Use the information on finite differences stored in the file FINDIF. This option requires a valid restart file for the wavefunctions, even when wavefunctions and coordinates are recalculated or read from the input file.

POTENTIAL

Read an old potential from the restart file. This applies to restarts for Kohn-Sham energy calculations.

KPOINTS

Restart with k points.

DENSITY

Restart with electronic density.

CONSTRAINTS

Restart with old values for constraints. This option is mainly for restraints with GROWTH option.

EXTRAP

Restart from a previously saved wavefunction history. See EXTRAPOLATE WFN for details.

ALL

Restart with all fields of RESTART file

RESTFILE

Section: &CPMD

The number of distinct RESTART files generated during CPMD runs is read from the next line.
The restart files are written in turn. Default is 1. If you specify e.g. 3, then the files RESTART.1, RESTART.2, RESTART.3 are used in rotation.

REVERSE VELOCITIES

Section: &CPMD

Reverse the ionic and electronic (if applicable) velocities after the initial setup of an MD run. This way one can, e.g., go ``backwards'' from a given RESTART to improve sampling of a given MD ``path''.

RFO ORDER=nsorder

Section: &CPMD

Rational function approximation combined with a quasi-Newton method (using BFGS) for optimization of the ionic positions is used [191]. A saddle point of order nsorder is searched for.

RHOOUT [BANDS,SAMPLE=nrhoout]

Section: &CPMD

Store the density at the end of the run on file DENSITY.
If the keyword BANDS is defined then on the following lines the number of bands (or orbitals) to be plotted and their index (starting from 1) have to be given. If the position specification is a negative number, then the wavefunction instead of the density is written. Each band is stored on its own file DENSITY.num. For spin polarized calculations besides the total density also the spin density is stored on the file SPINDEN. The following example will request output of the orbitals or bands number 5, 7, and 8 as wavefunctions:

            RHOOUT BANDS
              3
             -5 -7 -8

With the optional keyword SAMPLE the requested file(s) will be written every nrhoout steps during an MD trajectory. The corresponding time step number will be appended to the filename.

ROKS {SINGLET, TRIPLET},{DELOCALIZED, LOCALIZED, GOEDECKER}

Section: &CPMD

Calculates the first excited state using Restricted Open-shell Kohn-Sham theory [125]. By default, the singlet state is calculated using the delocalized variant of the modified Goedecker-Umrigar scheme, which is supposed to work in most cases. That is, for doing a ROKS simulation, it is usually sufficient to just include this keyword in the CPMD section (instead of using the LSE input). See 9.12 for further information.

ROTATION PARAMETER

Section: &TDDFT

The parameters for the orbital rotations in an optimized subspace calculation (see TAMM-DANCOFF) are read from the next line. The total number of iterations (default 50), the convergence criteria (default $10^{-6}$ ) and the step size (default 0.5) have to be given.

SCALED MASSES [OFF]

Section: &CPMD

Switches the usage of g-vector dependent masses on/off.
The number of shells included in the analytic integration is controlled with the keyword HAMILTONIAN CUTOFF.
By default this option is switched off.

SCALE [CARTESIAN] [S=sascale] [SX=sxscale] [SY=syscale] [SZ=szscale]

Section: &SYSTEM

Scale the atomic coordinates of the system with the lattice constant2 (see CELL). You can indicate an additional scale for each axis with the options SX, SY and SZ. For instance, if you indicate SX=sxscale, you give your x-coordinates between $0.$ and sxscale (by default $1.$ ). This is useful when you use many primitive cells. With the keyword CARTESIAN, you specify that the given coordinates are in Cartesian basis, otherwise the default with the SCALE option is in direct lattice basis. In all cases, the coordinates are multiplied by the lattice constants. If this keyword is present an output file GEOMETRY.scale is written. This file contains the lattice vectors in Åand atomic units together with the atomic coordinates in the direct lattice basis.

SHIFT POTENTIAL

Section: &CPMD

After this keyword, useful in hamiltonian diagonalization, the shift value $V_\mathrm{shift}$ must be provided in the next line. This option is used in the Davidson diagonalization subroutine and shifts rigidly the total electronic potential as $V_\mathrm{pot}(\mathbf{r}) \to V_\mathrm{pot}(\mathbf{r})+V_\mathrm{shift}$ then it is subtracted again at the end of the main loop, restoring back the original $V_\mathrm{pot}(\mathbf{r})$ that remains basically unaffected once that the calculation is completed.

SHOCK VELOCITY

Section: &SYSTEM

The shock velocity in meter/seconds for multi-scale shock calculations[8] is read in from the next line. See also the notes at the PARRINELLO-RAHMAN keyword.

SLATER [NO]

Section: &DFT

The $\alpha$ value for the Slater exchange functional [192] is read from the next line. With NO the exchange functional is switched off.
Default is a value of 2/3.
This option together with no correlation functional, allows for $X\alpha$ theory.

SMOOTH

Section: &DFT

A smoothening function is applied to the density [193].
The function is of the Fermi type.

$$f(G) = \frac{1}{% \displaystyle{1 + e^{\frac{\scriptstyle{G - G_{\scriptstyle cut}}} {\scriptstyle\Delta}}}}$$

G is the wavevector, $G_{cut} = \alpha G_{max}$ and $\Delta = \beta G_{max}$ . Values for $\alpha$ and $\beta$ have to be given on the next line.

SPLINE [POINTS, QFUNCTION, INIT, RANGE]

Section: &CPMD

This option controls the generation of the pseudopotential functions in g-space.
All pseudopotential functions are first initialized on a evenly spaced grid in g-space and then calculated at the needed positions with a spline interpolation. The number of spline points is read from the next line when POINTS is specified.
( The default number is 5000.) For calculations with the small cutoffs typically used together with Vanderbilt PP a much smaller value, like 1500 or 2000, is sufficient.
In addition it is possible to keep the Q-functions of the Vanderbilt pseudopotentials on the spline grid during the whole calculation and do the interpolation whenever needed. This option may be useful to save time during the initialization phase and memory in the case of Vanderbilt pseudopotentials when the number of shells is not much smaller than the total number of plane waves, i.e. for all cell symmetries except simple cubic and fcc.

SSIC

Section: &CPMD

Apply an ad hoc Self Interaction Correction (SIC) to the ordinary DFT calculation expressed in terms of total energy as

$$E^\mathrm{tot}-a\cdot E_H[m]- b\cdot E_{xc}[m, 0]$$

where $m(\mathbf{x}) = \rho_\alpha(\mathbf{x})-\rho_\beta(\mathbf{x})$ . The value of $a$ must be supplied in the next line, while in the present implementation $b$ is not required, being the optimal values $a=0.2$ and $b=0.0$ according to Ref. [194]. These are assumed as default values although it is not always the case [195]. Note that if you select negative $\{a, b \}$ parameters, the signs in the equation above will be reversed. The Hartree electronic potential is changed accordingly as $V_H[\rho] \to V_H[\rho] \pm a\cdot V_\mathrm{SIC}[m]$ , being

$$V_\mathrm{SIC}[m]=\frac{\delta E_H[m]}{\delta m(\mathbf{x})}$$

where the sign is $+$ for $\alpha$ spin and $-$ for $\beta$ spin components, respectively. Be aware that this keyword should be used together with $LSD$ (set by default).

STAGING

Section: &PIMD

Use the staging representation [151] of the path integral propagator. It is possible to impose a mass disparity between centroid and non-centroid coordinates by dividing the fictitious masses of only the non-centroid $s=2, \dots ,P$ replicas by the adiabaticity control factor FACSTAGE. This dimensionless factor must always be specified in the following line. Note: the eigen-frequencies of the $s>1$ replicas are changed by only $\sqrt{\mbox{FACSTAGE}}$ , see Ref. [141](b). Note: using FACSTAGE $\not= 1.0$ essentially makes no sense within the STAGING scheme, but see its use within CENTROID DYNAMICS and NORMAL MODES.

STATES

Section: &SYSTEM

The number of states used in the calculation is read from the next line.
This keyword has to preceed the keyword OCCUPATION.

STATES {MIXED,SINGLET,TRIPLET}

Section: &TDDFT

The number of states to be calculated is read from the next line. The type of state SINGLET, TRIPLET can be given for non-spinpolarized calculations. Default is to calculate one singlet state for LDA and 1 mixed state for LSD calculations.

STEEPEST DESCENT [ELECTRONS, IONS, CELL],[NOPRECONDITIONING],[LINE]

Section: &CPMD

NOPRECONDITIONING works only for electrons and LINE only for ions. Use the method of steepest descent for the optimization of wavefunction and/or atomic positions and/or cell.
If both options are specified in a geometry optimization run, a simultaneous optimization is performed.
Preconditioning of electron masses (scaled masses) is used by default. The preconditioning is controlled by the keyword HAMILTONIAN CUTOFF. Optionally preconditioning can be disabled.
For ions optimization, the steplength is controlled by the keywords TIMESTEP ELECTRONS and EMASS.

STEPLENGTH

Section: &LINRES

Step length for steepest descent and preconditioned conjugate gradient methods used in linear response calculations. Default is 0.1.

STORE {OFF} [WAVEFUNCTIONS, DENSITY, POTENTIAL]

Section: &CPMD

The RESTART file is updated every ISTORE steps. ISTORE is read from the next line. Default is at the end of the run.
Moreover, in the same line of the number ISTORE, you can specify the number of self-consistent iterations (with SC=number) between two updates of restart file. If OFF is specified , do not store wavefunctions and/or density (ISTORE is not necessary).

STRESS TENSOR

Section: &CPMD

Calculate the stress tensor every NSTEP iteration in a constant volume MD.
NSTEP is read from the next line. Works also for wavefunction or geometry optimization. In this case NSTEP is meaningless.

STRESS TENSOR

Section: &SYSTEM

In extension to the keyword PRESSURE the complete stress tensor in kbar can be specified. The stress on the system is read in the form:

$t_{11} t_{12} t_{13}$
$t_{21} t_{22} t_{23}$
$t_{31} t_{32} t_{33}$

STRUCTURE [BONDS, ANGLES, DIHEDRALS, SELECT]

Section: &CPMD

Print structure information at the end of the run.
Bonds, angles and dihedral angles can be printed. Dihedral angles are defined between 0 and 180 degrees. This might change in the future.
If the option SELECT is used the output is restricted to a set of atoms. The number of atoms and a list of the selected atoms has to be given on the next lines.

SUBTRACT [COMVEL, ROTVEL]

Section: &CPMD

If COMVEL is selected, the total momentum of the system is removed, if ROTVEL is selected the global angular momentum of the system is removed. Both options can be used separately and simultaneously. The subtraction is done each ncomv or nrotv steps, where the value is read in the next line.

By default this keyword is disabled.

Note1: The use of these keywords is strongly recommended for long runs (e.g. $t>10$ ps). Otherwise the whole system will start to translate and/or rotate toward a (random) direction with increasing speed and spinning. The ``relative'' translation within the system slows down correspondingly and thus the system effectively cools down. As a consequence dynamic properties, like self-diffusion coefficients or vibrational states populations will be wrong. Removing rotational momentum is not needed for dense systems as the interaction with particles across the periodic boundaries make rotations impossible.

This option should not be used for systems, where some atoms are kept at fixed positions, e.g. slab configurations. Here the center of mass may (or should) move. Due to the interactions with the fixed atoms, a drift of the whole system should be much reduced, anyways.

Note2: since the subtracted kinetic energy is put back into the system by simple rescaling of the ionic velocities, these options is not fully compatible with NOSE thermostats. Small v

SURFACE HOPPING

Section: &CPMD

Nonadiabatic dynamics involving the ground state and a ROKS excited state[196].

SURFACE

Section: &SYSTEM

Assume periodic boundary condition in $x$ - and $y$ -direction.

SYMMETRIZE COORDINATES

Section: &SYSTEM

The input coordinates are symmetrized according to the point group specified.
This only makes sense when the structure already is close to the symmetric one.

SYMMETRY

Section: &SYSTEM

The supercell symmetry type is read from the next line.
You can put a number or a keyword.

0

ISOLATED system in a cubic/orthorhombic box [72]with ISOLATED MOLECULE option activated. By default the Hockney method (see POISSON SOLVER) is used for solving the Poisson equations. You can use this option in combination with POLYMER or SURFACE for systems that are periodic in only 1 or 2 dimensions. The default Poisson solver is MORTENSEN in this case. See the Hints and Tricks section (section 9) for some additional requirements when calculating isolated system.

1

Simple CUBIC

2

FACE CENTERED CUBIC (FCC)

3

BODY CENTERED CUBIC (BCC)

4

HEXAGONAL

5

TRIGONAL or RHOMBOHEDRAL

6

TETRAGONAL

7

BODY CENTRED TETRAGONAL (BCT)

8

ORTHORHOMBIC

12

MONOCLINIC

14

TRICLINIC

Warning: This keyword should not be used with the keyword CELL VECTORS.

TAMM-DANCOFF [SUBSPACE,OPTIMIZE]

Section: &TDDFT

Use the Tamm-Dancoff approximation. This is the default for TDDFT calculations. Optionally, only a SUBSPACE of the occupied orbitals can be included in the calculation. The subspace can be optimized at each step (not recommended). Default is to use all states.

TASKGROUPS [MINIMAL,MAXIMAL,CARTESIAN]

Section: &CPMD

The number of taskgroups is read from the next line. The number of taskgroups has to be a divisor of the number of nodes in a parallel run; Cartesian Taskgroups use cartesian communicators.

TD_METHOD_A [functionals]

Section: &TDDFT

Use a different potential for the eigenvalue difference part of the response equations than was used to generate the ground state orbitals. The potential generating functional has to be given after the keyword. For possible functionals see the code. Most likely you want to use the SAOP functional.
This functional does not affect the choice of functional used in the TDDFT kernel. The kernel functional is set in the &DFT section. It is either the standard functional or the functional defined by the keyword LR KERNEL.

TDDFT

Section: &CPMD

Calculate the energy according to TDDFT. This keyword can be used together with OPTIMIZE GEOMETRY or MOLECULAR DYNAMICS BO. Use the &TDDFT section to set parameters for the calculation. This keyword requires RESTART LINRES.

TEMPCONTROL [IONS, ELECTRONS, CELL]

Section: &CPMD

The temperature of the ions in Kelvin or the fictitious kinetic energy of the electrons in atomic units or the kinetic energy of the cell in atomic units (?) is controlled by scaling.
The target temperature and the tolerance for the ions or the target kinetic energy and the tolerance for the electrons or the cell are read from the next line.

As a gentler alternative you may want to try the BERENDSEN scheme instead.

TEMPERATURE [RAMP]

Section: &CPMD

The initial temperature for the atoms in Kelvin is read from the next line. With the additional keyword RAMP the temperature can be linearly ramped to a target value and two more numbers are read, the ramping target temperature in Kelvin and the ramping speed in Kelving per atomic time unit (to get the change per timestep you have to multiply it with the value of TIMESTEP). Note that this ramping affects the target temperatures for TEMPCONTROL, BERENDSEN and the global NOSE thermostats.

TESR

Section: &SYSTEM

The number of additional supercells included in the real space sum for the Ewald term is read from the next line. Default is 0, for small unit cells larger values (up to 8) have to be used.

THAUTO

Section: &LINRES

The two values read from the next line control the switch to different optimizers for an automatic selection of optimizers during a linear response calculation. This also applies to the Z-vector optimization for TDDFT forces. The first value is the threshold for switching from conjugate gradients to DIIS (with compressed storage and averaged preconditioner, subspace size defined with ODIIS). The second value is the threshold for switching to DIIS with full storage and state dependent preconditioner. See also ZDIIS for specification of the subspace size.

TIGHTPREC

Section: &RESP

Uses a harder preconditioner. For experts: The Hamiltonian is approximated by the kinetic energy, the G-diagonal Coulomb potential and the KS-energies. The number obtained this way must not be close to zero. This is achieved by smoothing it with This is achieved by smoothing it with

$$x \to f(x) = \sqrt{x^2 + \epsilon^2} \; \; [\mathrm{default}]$$

or

$$x \to f(x) = (x^2 + \epsilon ^2)/x \; \; [\mathrm{this \; option}]$$

The HARD option conserves the sign of the approximate Hamiltonian whereas the default formula does never diverge.

TIMESTEP ELECTRONS

Section: &CPMD

The time step for electron updates in atomic units is read from the next line. This is can be used to tweak the convergence behavior of the wavefunction optimization in Born-Oppenheimer dynamics, where the default time step may be too large. see, e.g. PCG.

TIMESTEP IONS

Section: &CPMD

The time step in atomic units is read from the next line.

TIMESTEP

Section: &CPMD

The default time step in atomic units is read from the next line.
Default is a time step of 5 a.u. ( $1 a.u. = 0.0241888428$ fs).

TRAJECTORY [OFF, XYZ, DCD, SAMPLE, BINARY, RANGE, FORCES]

Section: &CPMD

Store the atomic positions, velocities and optionally forces at every NTRAJ time step on file TRAJECTORY. This is the default for MD runs. With the additional keyword XYZ the trajectory is also written in xyz-format on the file TRAJEC.xyz, similarly with the additional keyword DCD a trajectory in dcd-format (binary and single precision, as used by CHARMM, X-PLOR and other programs) is written on the file TRAJEC.dcd. If the keyword SAMPLE is given NTRAJ is read from the next line, otherwise the default value for NTRAJ is $1$ . A negative value of NTRAJ will disable output of the TRAJECTORY file, but e.g. TRAJEC.xyz will still be written every -NTRAJ steps. A value of 0 for NTRAJ will disable writing of the trajectory files altogether.

The TRAJECTORY file is written in binary format if the keyword BINARY is present. If FORCES is specified also the forces are written together with the positions and velocities into the file FTRAJECTORY. It is possible to store the data of a subset of atoms by specifying the suboption RANGE, the smallest and largest index of atoms is read from the next line. If both, SAMPLE and RANGE are given, the RANGE parameters have to come before the SAMPLE parameter.

TRANSITION MOMENT

Section: &PROP

Calculate the dipole transition matrix element.
On the following lines, the number of transitions and the involved orbitals are given. Example:

2
6	7
6	8

This calculates the dipole transition matrix elements between KS states 6 and 7, and between 6 and 8.

TROTTER DIMENSION

Section: &PIMD

The Trotter number $P$ , i.e. the number of ``replicas'', ``beads'', or ``imaginary time slices'' which are used in order to discretize the Feynman-Kac path integral of the nuclei, is read from the next line. If NORMAL MODES or STAGING is not activated the path integral is discretized in cartesian coordinates in real space (so-called ``primitive coordinates''). A discussion about controlling discretization errors and on estimating $P$ in advance is given in Ref. [197].

TROTTER FACTORIZATION OFF

Section: &CPMD

Do not use Trotter factorization to calculate free energy functional.
Remark: Place this keywords only after FREE ENERGY FUNCTIONAL; before it has no effect. Note: this keyword has nothing to do with path integral MD as activated by the keyword PATH INTEGRAL and as specified in the &PIMD section.

TROTTER FACTOR

Section: &CPMD

Solve $e^{-H/k_BT}$ directly using Trotter approximation
$\left( e^{-pH} \simeq e^{-pK/2}e^{-pV}e^{-pK/2}\right)$ .
The Trotter approximation is twice as fast.
The Trotter factor is read from the next line (typically 0.001 is very accurate).

VDW CORRECTION [ON,OFF]

Section: &CPMD

An empirical van der Waals correction scheme is applied to pairs of atom types specified with this keyword. This activates reading the corresponding parameters from the &VDW section. See VDW PARAMETERS for more details.

VDW PARAMETERS

Section: &VDW

Parameters for empirical van der Waals correction schemes are set with the keyword. This requires the VDW CORRECTION keyword to be set in the &CPMD section. For the GRIMME type (see below) an automatic assignment of the parameters can be requested by putting ALL GRIMME on the next line. Otherwise the number of pairs NVDW is read from the next line and followed by NVDW lines of parameters: TYPE, $\alpha$ , $\beta$ , $C_6^{\alpha\beta}$ , $R_0^{\alpha\beta}$ , and $d$ for each pair of atom types $\alpha$ and $\beta$ , where $\alpha$ and $\beta$ are the indexes of pseudopotentials (and their associated groups of atoms) in the order they are listed in the &ATOMS section. For type GRIMME only $\alpha$ and $\beta$ are required. If the other parameters are omitted, an internal table of parameters is used.

A presently implemented damped dispersion model, described by M. Elstner et al.[198], having the same form as that constructed by Mooij et al.[199], is activated by specifying C6 as TYPE. This model is expressed as

$$<tex2html_comment_mark>766 E_{vdW} = \sum_{ij} \frac{C_6^{\alpha\... ...ft(\frac{R^{\alpha\beta}_{ij}}{R^{\alpha\beta}_0} \right)^7 \right]} \right)^4.$$ (275)

A table of parameters appropriate for this particular model, using the PBE and BLYP functionals, is available [200].

Alternatively Van der Waals correction according to Grimme can be used[201] by selecting TYPE GRIMME.

$$E_{disp} = - s_6 \sum_{i=1}^{N_{at} -1} \sum_{j=i+1}^{N_{at}} \frac{C_6^{ij}}{R_{ij}^6} f_{dmp} (R_{ij})$$ (276)

Values of $C_6$ and $R_0$ which are not explicitly specified are taken from an internal table with the data from[201].

VDW-CUTOFF

Section: &VDW

On the next line the short range cutoff of van der Waals correction has to be specified. The default value is $10^{-2}$ .

VDW-CELL

Section: &VDW

The number of additional supercells to be included in the sum of van der Waals correction.

VELOCITIES

Section: &ATOMS

Sets an initial velocity for specified atoms.
The first line contains first the total number of specified atomic velocities followed on the same line by the list of atomic numbers for which the velocities will be read. On each of the following lines the x, y and z coordinates of the velocities of an atom have to be specified. These values will ignored in case of starting with RESTART VELOCITIES.

This section of the input has to be terminated by a line containing END VELOCITIES.

NOTE: these velocities are rescaled to produce the initial temperature as specified by TEMPERATURE. The default temperature, however, is 0K, so you have to set the matching temperature or your initial velocities will be useless.

VIBRATIONAL ANALYSIS [FD, LR, IN], [GAUSS, SAMPLE, ACLIMAX]

Section: &CPMD

Calculate harmonic frequencies by finite differences of first derivatives (FD) (see also keyword FINITE DIFFERENCES), by linear response to ionic displacements (LR) or from a pre-calculated Hessian (IN). K-point sampling is currently possible using finite differences. If the option GAUSS is specified, additional output is written on the file VIB1.log which contains the modes in a style similar to GAUSSIAN 98 output. This file can be read in and visualized with programs like MOLDEN or MOLEKEL. The option SAMPLE reads an integer from the next line. If this number is 2 an additional file VIB2.log containing the lowest modes is written. The default value is 1. If the option ACLIMAX is specified, additional output is written on the file VIB.aclimax which contains the modes in a style readable by aClimax (http://www.isis.rl.ac.uk/molecularspectroscopy/aclimax/). If a section &PROP is present with the keyword DIPOLE MOMENT[BERRY] or DIPOLE MOMENT[RS], the Born charge tensor is calculated on the fly. See also the block &LINRES and the keywords RESTART PHESS and HESSIAN {DISCO,SCHLEGEL,UNIT} PARTIAL.

WANNIER DOS

Section: &CPMD

Outputs the projected density of states of the Wannier orbitals (file WANNIER_DOS) and the KS hamiltonian in the Wannier states representation (file WANNIER_HAM).

When running MOLECULAR DYNAMICS CP the files WANNIER_DOS and WANNIER_HAM solely written at the last step.

WANNIER MOLECULAR

Section: &CPMD

Generates effective molecular orbitals from the Wannier representation. It first attributes Wannier orbitals to molecules and then diagonalizes by molecular blocks the KS Hamiltonian.

Does not work with MOLECULAR DYNAMICS CP.

WANNIER OPTIMIZATION {SD,JACOBI}

Section: &CPMD

Use steepest descent or Jacobi rotation method for the orbital localization.
Default are Jacobi rotations.

WANNIER PARAMETER

Section: &CPMD

W_STEP, W_EPS, W_RAN, W_MAXS are read from the next line. W_STEP is the step size of the steepest descent algorithm used in the optimization procedure (default value 0.1). W_EPS the convergence criteria for the gradient (default value $1.e-7$ ). W_RAN the amplitude for the initial random rotation of the states (default value 0.0). W_MAXS is the maximum steps allowed in the optimization (default value 200).

WANNIER REFERENCE

Section: &CPMD

The vector W_REF is read from the next line, which consists of 3 coordinates $x, y, z$ . These are assumed as the origin for the WFCs positions and related ionic coordinates (i.e. $\mathbf{R}_I \to \mathbf{R}_I-(x, y, z)$ ). The default value is the center of the supercell, if CENTER MOLECULE keyword is active (Note, that this is implicitly turned on, for calculations with SYMMETRY 0). Otherwise it is set to (0,0,0), which is usually not the center of the box. In order to get the best results displaying the IONS+CENTERS.xyz file this parameter should be set explicitly.

WANNIER SCREENING {WFC,DENSITY,DIAG}

Section: &DFT

Read DWFC DWFMAX from the next line.
Perform the calculation of exact exchange using Wannier functions. Orbital pairs are screened according to the distance of the Wannier centers (WFC, cutoff DWFC), the density overlap (DENSITY, cutoff DWFMAX), or only the diagonal terms are included (DIAG).

WANNIER SERIAL

Section: &CPMD

Requests that the calculation of Wannier functions is performed using the serial code, even in parallel runs.

WANNIER TYPE {VANDERBILT,RESTA}

Section: &CPMD

Indicates the type of Wannier functions. Vanderbilt type is the default.

WANNIER WFNOUT [ALL,PARTIAL,LIST,DENSITY,SPREAD]

Section: &CPMD

Controls the printing of Wannier functions. Either all or only some of the functions can be printed. This will be done at the end of each calculation of Wannier functions. For PARTIAL output you have to give the indices of the first and the last wannier function to print; the LIST directive follows the syntax of RHOOUT BANDS. Using the SPREAD flag the list of functions to write is determined in every step based on the spread value relative to the reference value given on the following line. With a positive reference value all Wannier functions with a spread larger than the reference will be written out; with a negative reference value all Wannier functions with a spread smaller than the absolute of the reference value will be written out.

Example:

            WANNIER WFNOUT PARTIAL
               5  8

XC_ANALYTIC

Section: &LINRES

Use analytic second derivatives of the XC functional (only available for some LDA functionals)

XC_EPS

Section: &LINRES

Finite difference parameter for XC derivative. Default is $5 \cdot 10^{-4}$ .

XC_DD_ANALYTIC

Section: &LINRES

Use analytic second derivatives of the XC functional, see Ref [3] (only available for some LDA and gradient-corrected functionals). For the analytic third derivatives of some LDA XC functionals, XC_ANALYTIC can be combined with this keyword

ZDIIS

Section: &LINRES

The subspace size for the optimizer is read from the next line.

ZFLEXIBLE CELL

Section: &SYSTEM

Specifies a constraint on the super cell in constant pressure dynamics or geometry optimizations. The supercell may only shrink or grow in z-direction. Should be very useful for ``dense slab'' configurations, e.g. a water layer between solid slabs.
Please note: this is by no means intended to give a statistically meaningful ensemble, but merely to provide a tool for efficient equilibration of a specific class of system.

[TSDE, TSDP, TSDC] [NOPRECONDITIONING] NOPRECONDITIONING only electrons

Section: &CPMD

Short forms for the different STEEPEST DESCENT options.

n-CENTER CUTOFF

Section: &PROP

The cutoff for printing the n-center shared electron numbers is read from the next line. All one and two center terms are printed.