[Pw_forum] the sum of the born effective charge in phonon calculation

[程迎春]

Dear Prof. Eyvaz lsaev,
        Thank you for your suggestion.  I have another problem concerning
this question.  The keyword "conv_thr" is the convergence threshold for scf,
and the "th2_ph" is the threshold for selfconsistency in phonon
calculation.  What is the difference between the two keywords?   Previously
I thought that the two keywords are both for wavefunction optimization and
they should have the same meaning.



2009/7/1 Eyvaz Isaev <eyvaz_isaev at yahoo.com>

>
> Dear Cheng,
>
> >     conv_thr = 1.D-12,
> You wast time with this threshold. Use less strong criteria.
>
> >           -2.01782
> >            2.04775
>
> I would say the Born charges are equivalent (by absolut values) with a
> numerical noise. Within this noise charges' sum is zero.
>
> >   tr2_ph=1.0d-12,
> Try d-14, and more ecutwfc.
>
>
>

 --
Y. C. Cheng
Department of Physics
Nanjing University
Nanjing 210093
P. R. China
Tel: 86-25-83592907
Email: yccheng.nju at gmail.com
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