[Pw_forum] problem with scf and nscf calculation!!

[Federico Iori]

Thanks Conor.... I'm goning to try this now!..

...but I still dont' understand why I cant't get the right band 
structure with the PW-3.0 version.

Infact another "strange thing" happen: when my system is semiconductor 
(all the valence states are doubly occupied)  I can get the right band 
strcuture both with the PW-3.0 and PW-3.2 calculation. BUT when my 
system become metallic (inserting a substitutional impurity) and I have 
a semi-occpudied level, the calculation for the band dont' work 
anymore........!!!
sigh!

idee???


Conor Hogan ha scritto:
> Hi Federico,
> When doing nscf/bands calculations with later versions of PWscf, and you
> want well converged states, you should set diago_full_acc = .true. ,  set
> diago_thr_init to a smaller value than the default (this determines the
> precision of ther nscf calculation), and usually use a few more bands than
> what you need will help. The Doc/INPUT_PW for 3.2 has a fair description
> of these. As for bands/nscf, I notice that bands will read efermi from
> data-file.xml while nscf does not, which might mean eigenvalues are not
> aligned, but this is just a guess.
> cheers
> Conor
>
> On Mon, March 12, 2007 4:33 pm, Federico Iori said:
>   
>> Hi pw users!
>>
>> I'm doing some calculation on metallic systems but I have several
>>     
> problems with scf and than nscf (or bands) calculation for the band
> structure calcualtion:
>   
>> what happen is that the eigenvalues calculated with a SCF calculation
>>     
> and with a NSCF (PWversion =< 3.0) or BANDS (for PWversion >= 3.1) on
> the same kpoints differ: the band strcture is completely different in
> the NSCF (I should say wrong,because the character of the electronic
> structure completely change) with respect the SCF calculation.
>   
>> I use this smearing:
>>
>>         occupations='smearing',
>>         smearing='gaussian',
>>         degauss=0.005,
>>
>>
>>
>> Could someone suggest me something, please? ( a part to change job of
>>     
> course....)
>   
>> cheers,
>> federico iori.
>>
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>>     
>
>
> ----
>
> Dr. Conor Hogan                                --- -----  ---   --- 
> Dipartimento di Fisica e CNR-INFM             |      :   |     :    
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> http://www.fisica.uniroma2.it/~cmtheo-group/  European Theoretical
>                                               Spectroscopy Facility 
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