[CPMD-list] Problems optimizing monoclinic unit cell

[Dr. Balasubramanian Sundaram]

Dear Ewald,
    We have been doing geometry optimization (ion coordinates) in 
a monoclinic cell, without problems. Our CPMD version 3.9.1. 
I feel that the following lines in your input file may not be correct.

> CELL
> 5.0872  2.314338  1.073321  0.0  -0.374493314  0.0

In the new version (v. 3.9.1), in file "sysin.F", there are a few lines
that
say:
      ELSE IF (IBRAV.EQ.12) THEN
         IF ((ABS(CELLDM(5)).GT.BOXEPS)
     $        .OR.(ABS(CELLDM(6)).GT.BOXEPS)) THEN
            WRITE(0,*) 'SUPERCELL IS NOT MONOCLINIC'
            WRITE(0,'(A,A)') 'EXPECTED FORM:',
     $           ' a b c d 0.0 0.0'
            CELLOK=.FALSE.
         ENDIF

It appears that the correct way to put the cell info for you would be:

> CELL
> 5.0872  2.314338  1.073321 -0.374493314  0.0 0.0

The previous version (v. 3.7.2) did not have this check and error msg. 
This is probably a reason why the molecular conformation got messy.

Best Wishes,
Bala



Ewald Pauwels wrote:
> 
> Dear all,
> 
> Does anybody have any experience with applying CPMD on monoclinic crystals?
> The system I am studying contains four (organic) molecules in the unit
> cell. When I optimize these molecules (only the atomic coordinates - not
> the cell constants), I find that the unit cell no longer satisfies the
> original symmetry. I.e. all four molecules have a substantially
> different conformation!
> 
> I suspect that I must be doing something wrong here. Below is my inputfile.
> 
> Thanks in advance,
> Ewald.
> 
> -------------------------------------------------------
> inputfile
> -------------------------------------------------------
> &CPMD
>  RESTART LATEST GEOFILE WAVEFUNCTION
>  OPTIMIZE GEOMETRY
>  LSD
>  ODIIS NO_RESET=50
>   10
>  TIMESTEP
>   20
>  PRINT
>   10
>  STRUCTURE BONDS ANGLES
> &END
> 
> &SYSTEM
>  ANGSTROM
>  SYMMETRY
>  12
>  CELL
>  5.0872  2.314338  1.073321  0.0  -0.374493314  0.0
>  CUTOFF
>  25.
>  MULTIPLICITY
>  1
> &END
> 
> &ATOMS
> *C_VDB_U BINARY NEWF
>  LMAX=P
>  8
>   0.218182218417937  1.473520453  0.333090471110274
>   0.732546560623109  1.717103823  -1.08374897292691
>   1.30308357695184  7.360020453  2.1982999039374
>   0.788719234746671  7.603603823  3.61513934797459
>   -0.218182218417937  -1.473520453  -0.333090471110274
>   -0.732546560623109  -1.717103823  1.08374897292691
>   1.73944801378772  4.412979547  2.86448084615795
>   2.25381235599289  4.169396177  1.44764140212077
> *N_VDB_U BINARY NEWF
>  LMAX=P
>  4
>   2.03113800324446  1.040509513  -1.31410549705625
>   -0.509872207874679  6.927009513  3.84549587210393
>   -2.03113800324446  -1.040509513  1.31410549705625
>   3.55240379861424  4.845990487  1.21728487799143
> *O_VDB_U BINARY NEWF
>  LMAX=P
>  8
>   1.05333382374583  1.104201443  1.19695275049904
>   -1.00750738194352  1.676251513  0.53944941448416
>   0.467931971623952  6.990701443  1.33443762454863
>   2.5287731773133  7.562751513  1.99194096056352
>   -1.05333382374583  -1.104201443  -1.19695275049904
>   1.00750738194352  -1.676251513  -0.53944941448416
>   2.57459961911561  4.782298557  3.72834312554672
>   0.513758413426261  4.210248487  3.07083978953184
> *H_VDB_U BINARY NEWF
>  LMAX=S
>  20
>   2.33817143317496  1.18130282  -2.29299415508719
>   2.75812420631155  1.37791192  -0.67745575495101
>   1.93653355901116  0.03473035  -1.14763114043162
>   0.875530385150063  2.77889892  -1.22357285168305
>   0.0131007466085907  1.35318862  -1.81758891709173
>   -0.816905637805185  7.06780282  4.82438453013487
>   -1.23685841094177  7.26441192  3.20884612999869
>   -0.415267763641377  5.92123035  3.67902151547929
>   0.645735410219716  8.66539892  3.75496322673072
>   1.50816504876119  7.23968862  4.34897929213941
>   -2.33817143317496  -1.18130282  2.29299415508719
>   -2.75812420631155  -1.37791192  0.67745575495101
>   -1.93653355901116  -0.03473035  1.14763114043162
>   -0.875530385150063  -2.77889892  1.22357285168305
>   -0.0131007466085907  -1.35318862  1.81758891709173
>   3.85943722854474  4.70519718  0.23839621996049
>   4.27939000168133  4.50858808  1.85393462009667
>   3.45779935438094  5.85176965  1.38375923461606
>   2.39679618051984  3.10760108  1.30781752336463
>   1.53436654197837  4.53331138  0.713801457955944
> &END
> 
> &DFT
>  LDA CORRELATION PZ
>  FUNCTIONAL BP
>  GC-CUTOFF
>  5.D-5
> &END
> ------------------------------------------------------------------
> 
> --
> Ewald Pauwels
> Centre for Molecular Modelling
> Laboratory of Theoretical Physics
> Ghent University
> Proeftuinstraat 86
> B-9000 Gent
> Belgium
> ewald.pauwels at UGent.be
> +32 9 264 65 76
> 
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