[Pw_forum] How to get the most reliable dos/pdos results

[Peng Chen]

Dear Stefnao,

Thanks for your reply. Energy convergence (to 0.002 Ry) tests with a series
of ecutwfc, erho, degauss, kpoints parameters have been done (I am not sure
if there are other convergence tests for DOS). The experimental result will
be available later, I just want to make sure I am not doing something wrong
with choosing parameters. Someone told me to compare with all-electron
 calculation results. I actually did it with Exciting code, but it was
running for two weeks and  a power outage occurred...

On Sun, Jun 3, 2012 at 2:40 AM, Stefano Baroni <baroni at sissa.it> wrote:

> Dear Peng,
>
> I do not know nor anybody here (nor elsewhere) could. Suppose somebody
> does and tells you "3". What use would you do of that info? Would you use
> "3" and justify your choice by the advice of Mr. XXX as read on mailing
> list YYY?
>
> The correct way to proceed is: 1) form an idea of the level of accuracy
> you need; 2) perform a convergence test until your target accuracy is met;
> 3) stop there and don't ask for more accuracy than you actually need,
> unless you want to test a specific algorithm/code and your level of
> understanding of it.
>
> Good luck!
> SB
>
> On Jun 3, 2012, at 4:44 AM, Peng Chen wrote:
>
> Dear QE users,
>
> I tried several dos/pdos calculations with different parameters listed in
> the table below. The  results are a little different.
> I am not sure which result is more reliable when the experimental results
> are not available.
>
>                                  scf
>                          nscf
> 1. dos/pdos      smearing (mv,degauss=0.01)                  tetrahedra
> 2. dos/pdos      smearing (mv,degauss=0.01)              smearing
> (mv,degauss=0.01)
> 3.  dos               tetrahedra
>        tetrahedra
>      pdos             smearing (mv,degauss=0.01)              smearing
> (mv,degauss=0.01)
>
>
>
> --
>   Best Regards.
>         Peng
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>
> ---
> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
> http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /
> stefanobaroni (skype)
>
> La morale est une logique de l'action comme la logique est une morale de
> la pensée - Jean Piaget
>
>
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-- 
  Best Regards.
        Peng
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