[CPMD-list] How to get the CONSTRAINT file?

[Juerg Hutter]

Hi

you are using "trivial" constraints. For this type of
constraints (just fixed atomic coordinates) it is not
necessary to perform SHAKE/RATTLE iterations. The constraint
forces are equal to the calculated forces on the atom.
This type of constraint is not often used in thermodynamic
integration and CPMD is not writing the forces to the
CONSTRAINT file.

You can print the forces to the output file using the
PRINT command or add a write statement in the forces
routine.

regards

Juerg

----------------------------------------------------------
Juerg Hutter                   Phone : ++41 1 635 4491
Physical Chemistry Institute   FAX   : ++41 1 635 6838
University of Zurich           E-mail: hutter at pci.unizh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
----------------------------------------------------------


On Mon, 11 Nov 2002, Martin Konopka wrote:

> Dear CPMD community,
>
> can anybody tell me how to force CPMD to produce the CONSTRAINT file
> and to do constraint MD using the Blue Moon ensemble prescription?
> I am doing a Car-Parinello constraint simulation but I can not get
> the CONSTRAINT file. According to the manual, it should be produced in
> constraint MD runs automatically.
> I am using Vanderbilt pseudpotentials and the OLDCODE keyword.
> The program otherwise works, constraints are not ignored, the only
> problem is with the CONSTRAINT file.
> Below I put most of my input file.
> Thanks.
>
> Martin Konopka.
>
>
> &CPMD
>   RESTART WAVEFUNCTIONS COORDINATES VELOCITIES NOSEP LATEST
>   RESTFILE
>     2
>   STORE
>     200
>   MOLECULAR DYNAMICS CP
>   MAXSTEP
>     5000
>   NOSE IONS MASSIVE
>     300.0D0 4000.0D0
>   NOSE PARAMETERS
>     3 3 0 6.0 15 4
>   EMASS
>     200.0D0
>   TIMESTEP
>     5.0D0
>   ISOLATED MOLECULE
>  SPLINE POINTS QFUNCTIONS
>     2001
>   CENTER MOLECULE OFF
>   MEMORY BIG
>   LSD
> &END
> &DFT
>   OLDCODE
>   GRADIENT CORRECTION PBEX PBEC
>   GC-CUTOFF
>     5.0D-5
> &END
> &SYSTEM
>   SYMMETRY
>     8
>   CELL ABSOLUTE
>     23.0D0  30.0D0  36.0D0  0.0D0  0.0D0  0.0D0
>   TESR
>     4
>   CUTOFF
>     25.0D0
>   CHARGE
>     0
> &END
> &ATOMS
> *H.uspp BINARY NEWF TPSEU
>   LMAX=S
>   5
> ...                 (I have 4 species and 13 atoms in total.)
> ...
> CONSTRAINTS
>   FIX ATOMS
>     1
>     12
>   FIX COORDINATES
>     1
>     6 1 1 0
> END CONSTRAINTS
> &END
>
> ------------------------------------------------------------------------
> Dr. Martin Konopka             http://www.ccms.elf.stuba.sk/konopka.html
> Department of Physics                            tel: +421 (0)2 60291714
> Slovak University of Technology (FEI STU)        fax: +421 (0)2 65411483
> Ilkovicova 3, 812 19 Bratislava, Slovakia
> ------------------------------------------------------------------------
>
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