[Pw_forum] nosym=.true. in molecular dynamics by PWSCF

[Axel Kohlmeyer]

On 1/9/07, Lawrence Lee <lawrence_lee_lee at yahoo.com.hk> wrote:
> Dear all,
>
> Is it really necessary that when using PWSCF to do molecular dynamics, the
> following:
>
> nosym=.true.
>
> had to be used? If yes, why?

please look at the documentation of the nosym flag!

pw.x tries to minimize the number of k-points needed by
eliminating symmetry equivalent ones. those can be quite
a few, if you have a very symmetric starting structure.

as soon as you move atoms, however, those k-points may
no longer be equivalent, but the code assumes that the
number of k-points does not change during a calculation.

similarly point group symmetries are used to speed
up the calculation in several places.

cheers,
   axel.

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