[CPMD-list] Is it possible to keep the POINT GROUP fixed in geometry optimization and any molecular dynamics?

[Axel Kohlmeyer]

On Fri, 28 Mar 2008, Charles Chen wrote:

CC> Dear CPMD users,

dear charles,

CC> I have the same question as Rex in 2006.

please provide an URL.

[...]

CC> I am trying to optimize TiO2 anatase with the following input file:

CC> > &SYSTEM
CC> >   SYMMETRY
CC> >   6
CC> >   SCALE
CC> >   ANGSTROM
CC> >   CELL ABSOLUTE DEGREE
CC> >   3.776 3.776  9.486  90.0  90.0  90.0
CC> >   DUAL
CC> >   8
CC> >   CUTOFF
CC> >   25.0
CC> > &END

hmmm.... that small a cell and no k-points?

[...]

CC> But the output with Cartesian coordinates is off the symmetry.
CC> >  O  0.0000  0.0000  1.6696
CC> > Ti  0.0000  0.0000  0.1014
CC> Anything wrong?

i'd suspect insufficient sampling of the BZ, 
i.e. the original structure is not stable with 
gamma only.

cheers,
 axel.

CC> 
CC> Thanks!
CC> 
CC> Charles Chen
CC> 
CC> 
CC> 
CC> 

-- 
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Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
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