On Wed, 10 Mar 2010 13:03:05 +0100, Masoud Nahali <masoudnahali at live.com> wrote: > 1. fixing or changing the cell symmetry through the calculation.
Stress and force components that would break the symmetry are always zero... by symmetry > 2. fixing or optimizing the cell size through the calculation. Just use relax instead of vc-relax, if you mean the *volume* of the cell, than there is a keyword for that but unluckily it does not work very well with bfgs... > 3. optimizing all positions without considering any restrictions. This is the default, however you can fix the position of one or more atoms along any cartesian direction if you wish. best regards -- Lorenzo Paulatto *** Note: my affiliation has changed! please send future correspondence to: <Lorenzo.Paulatto at impmc.upmc.fr> *** post-doc @ IMPMC/UPMC - Universit? Paris 6 phone: +33 (0)1 44 27 74 89 www: http://www-int.impmc.upmc.fr/~paulatto/ previously: phd student @ SISSA & DEMOCRITOS (Trieste) phone: +39 040 3787 511 www: http://people.sissa.it/~paulatto/
