[Pw_forum] Tetrahedra occupations not provided for NSCF and DOS

[B S Bhushan]

Dear Dr. Lorenzo,

Thank you very much for such a clear explanation. You saved my 20 days of
work.

Regarding the second passage of your reply, I have also extracted the
electronic DOS of graphene with tetrahedra occupations and the resultant
DOS is fine.

Thank you very much Dr for your precious time.



On Wed, May 24, 2017 at 12:22 PM, Lorenzo Paulatto <
lorenzo.paulatto at impmc.upmc.fr> wrote:

> Dear Bushan,
> it is perfectly fine. Actually, smearing is in general more reliable and
> better tested than tetrahedra. The latter can be more efficient, it may
> give nicer picture for the density of states (DOS), and avoids introducing
> an arbitrary smearing value.
>
> In particular, in the case of graphene, using tetrahedra can be plain
> wrong; if I remember correctly it does not work properly for 2D systems.
> This is quite obvious when doing the phonon DOS, that does not go to zero
> at zero frequency, as it should. I don't know if it is a problem also for
> the electronic DOS.
>
>
> On 24 May 2017 at 08:41, B S Bhushan <ecebhushan at gmail.com> wrote:
>
>> Dear QE experts,
>>
>> I have extracted DOS of a 50 atom graphene system.
>> While performing SCF I have considered occupations=smearing, smearing=mv,
>> degauss=0.005.
>> However, while performing "NSCF", I forgot to change the occupations to
>> Tetrahedra and left the occupations option same as in SCF
>> (occupations=smearing, smearing=mv, degauss=0.005).
>>
>> My doubt is, Is it OK to have non-tetrahedra occupations for NSCF ?.
>> Can I proceed to further calculations on the basis of obtained DOS for
>> this system?
>>
>> Thank you very much giving your precious time.
>>
>> your's sincerely,
>> B S Bhushan
>>
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>
>
>
> --
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> phone: +33 (0)1 442 79822 / skype: paulatz
> www:   http://www-int.impmc.upmc.fr/~paulatto/
> mail:  23-24/421 Boîte courrier 115, 4 place Jussieu 75252 Paris CX 05
>
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