[Pw_forum] change of crystal symmetry during vc-relax calculations with pressure

[Paolo Giannozzi]

On Fri, 2013-06-14 at 07:18 +0000, saqib javed wrote:

> Can vc-relaxation at a given pressure with bfgs method allows for
> change of crystal symmetry ?? 

no, but only the symmetry as found by the code is conserved;
"accidental" symmetries, e.g. lattice vectors a and b having 
equal length but no symmetry operation sending a into b, may 
be easily lost due to numerical noise.

Paolo
-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222