[Pw_forum] about fermi level

[Q.J.Wang]

Dear Haruhiko Dekura

>Message: 3
>Date: Wed, 30 Dec 2009 01:30:28 +0900
>From: Haruhiko Dekura <dekura at cmp.sanken.osaka-u.ac.jp>
>Subject: Re: [Pw_forum] about fermi level
>To: PWSCF Forum <pw_forum at pwscf.org>
>Message-ID:
> <B22CEA00-6D59-4FF1-8B8E-DBC4F48E4CF3 at cmp.sanken.osaka-u.ac.jp>
>Content-Type: text/plain; charset=us-ascii
>
>Dear Wang 
>
>I think that the Fermi level obtained with nscf run reaches sufficient value only when the KS energy spectrum ( hence, also scf-potential ) is well converged in scf calculation. 
 
How to judge the KS energy spectrum is well converged or not in scf calculation ? 
Can you give me special examples or make some elaborate on this ? what should I do when encounter this problem ?
I found many pwscf users encounter the same problem and they don't know which fermi level is used to plot DOS when fermi level is different between scf.out and nscf.out.
Thank you very much for you help !

>Therefore, in my guess, if you can see the convergence of KS levels as well as total energy against the increase of k-point (and width of smearing), the Fermi-level obtained with DOS calculation is more reliable value. So, I think the problem is depending on the convergency of your scf-potential after scf calculation. If you don't have converged one,  both Fermi-levels ( obtained by scf or nscf run) so obtained are both not sufficient.          
>What do you think ?
>
>
>Haruhiko Dekura
>
>PH.D. student
>Osaka university 
>
>
>On 2009/12/29, at 23:51, Q.J.Wang wrote:
>
>> Dear all
>>      After I run scf(k-points,3*3*3)with 'smearing'  , I increase the k-points (5*5*5)and run nscf with 'tetrahedra' in order to get DOS,but the fermi levels have little difference between the scf.out and nscf.out . Which I should select when plot DOS pictuce ?
>>      I have search in the forum ,but still haven't the correct answer .

--

Best regards
 
Q.J.Wang
 
XiangTan University 
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