[Pw_forum] Single point energy calculation within PWSCF.

[Hongsheng Zhao]

On 05/25/2011 02:53 PM, Emine Kucukbenli wrote:
> I was thinking that you were trying to optimize the calculation
> parameters however with this post I am lost.I will give a generic
> answer:
>
> Before starting to work on a system, you need to optimize the
> calculation parameters, much like an experimentalist optimizing their
> machine set up before an experiment.
>
> You need to make sure that what you will get, once you do the desired
> calculation, (like a desired experiment) would be sensible data. This
> is a preparation scheme_before_  the actual calculations.
>
> In this preparation process, you need to check the convergence of
> energy, and/or forces, pressure etc, basically whatever interests you,
> or whatever the interested property is sensitive to. And by
> convergence, I mean convergence with respect to calculation
> parameters: ecutwfc/rho ; kpoints ; smearing for metals; box size for
> isolated systems, convergence thresholds etc ..again, whatever is
> relevant.
>
> Once you know the optimum values for these parameters, you can do some
> applications: One of them might be finding the equilibrium lattice
> parameter. If  so, now you can run a "vc-relax" calculation to get the
> zero pressure structure..
>
> Hope this made any sense and didnt confuse you even more.
> cheers,
> emine kucukbenli, phd student, sissa, italy
Thanks a lot for your systematic analysis ;-)

Regards
-- 

Hongsheng Zhao<zhaohscas at yahoo.com.cn>
School of Physics and Electrical Information Science,
Ningxia University, Yinchuan 750021, China