[Pw_forum] problems with pressure calculation

[Eduardo Ariel Menendez Proupin]

Dear Paolo,
Thanks for your advice. The wild pressure oscillations dissapear using a
smaller value of con_thr.

>it looks like a nonlinear interaction between symmetry and insufficient
>convergence of self-consistency. If you reduce the convergence >threshold
>to conv_thr=1.0e-8 or so (default is 10e-6) the jumps disappear; same if
>you use all symmetries, whether their fractional translation is
>commensurate or not with the FFT grid (option use_all_frac). I guess
>that the discrepancy wrt previous versions has a similar origin.

>The default value for the convergence threshold is good if you are
>interested in energies, reasonable if you are interested in forces,
>not so good for stress and pressure

Best regards
-- 
Eduardo Menendez Proupin
Departamento de Fisica, Facultad de Ciencias, Universidad de Chile
URL: http://fisica.ciencias.uchile.cl/~emenendez
*"Lograremos el anhelado desarrollo cuando sea la ciudadanía, y no los
científicos, la que pida más ciencia para Chile." J. Babul*
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