[Pw_forum] maybe a bug in the QE 4.0.4 (Stefano Baroni)
baroni at sissa.it
Thu Apr 2 08:03:50 CEST 2009
I am confused: no electric field, no Berry phase - what I suggested
you to try is whether the stress calculated from finite differences
and from the Hellmann-Feynman theorem give the same result (no Berry
phase in either case). I am confident they do. SB
On Apr 2, 2009, at 7:12 AM, hanghui chen wrote:
> Yes. At vanish electric field, even with USPP the stress is the same
> as the normal calculation (without using Berry Phase method).
> Hope this helps.
> Is your calculated stress OK with USPP at vaishing electric field?
> On Apr 1, 2009, at 4:48 PM, hanghui chen wrote:
> > Dear PWscf developers and in particular Professor Baroni,
> > Thank you very much for your instructions.
> > I did the test to check the forces and stress in the Berry
> > phase method with the ultrasoft pseudopotential. The forces are
> > correct but the stress is around 50% smaller. I am not sure whether
> > it is due to the ultrasoft pseudopotential or not.
> > I would greatly appreciate it if the developers of QE could
> > reexamine the calculation of stress in the Berry phase method with
> > the ultrasoft pseudopotential.
> > Best wishes.
> > Hanghui Chen
> > Department of Physics,
> > Yale University
> Pw_forum mailing list
> Pw_forum at pwscf.org
Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center -
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /
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