[Pw_forum] force and stress in the Berry phase method
baroni at sissa.it
Tue Mar 31 06:35:02 CEST 2009
Dear Hanghui Chen,
On Mar 30, 2009, at 10:20 PM, hanghui chen wrote:
> Dear PWSCF users,
> In addition to my previous email, I would like to know: if I use
> ultrasoft psedopotential, are the forces and stress correctly
> calculated in the Berry phase method in the latest version 4.0.4?
forgive my answering your question in a rather indirect and
this is a question that you could (actually, should) easily answer
yourself. just repeat your calculation with (slightly) distorted
atomic positions / cell parameters, calculate forces and stresses by
finite differences, and compare with the results of the code. this
way, you would do yourself and us a favor. yourself, because you would
learn not to trust ANY code (not even the best, i.e. QE); us because
if the code is supposed to give the right answer and id doesn't, then
you will have helped discover a bug ...
> Thank you very much.
Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center -
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /
La morale est une logique de l'action comme la logique est une morale
de la pensée - Jean Piaget
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