[Pw_forum] Tow question about band gap and occupations= 'smearing or fixed

[bramha pandey]

2012/3/28 Nicola Marzari <nicola.marzari at epfl.ch>

>
>
> There is no harm in using smearing in a semiconductor/insulator (only
> an increased cost in the calculation).
>
> To get the band gap you need in any case the empty states - but note that
> unless you know at which k-point the band gap is, you need to do a close
> examination of the entire band structure.
>
> last, of course the dft band gap is fairly useless.
>

Dear Sir, so what approch should we take to calculate the band gap of
semiconductor structure in QE...Thanks in advanced for your kind response.

>
>                        nicola
>
>
> On 28/03/2012 11:25, sufyan wrote:
> > Dear quantum espresso user, i study a case with different constrain and
> > under some constrain this case changes from conductor to semiconductor
> > and vers-versa and I have a question firstly about "occupations=
> > 'smearing or fixed '" what can i do with it ? secondly Does the pw.x
> > give the band gap as numerical results in the out file ? thanks sufyan
> naji
> >
> >
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>
> --
>
> ----------------------------------------------------------------------
> Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
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-- 
Thanks and Regards
Bramha Prasad Pandey
GLA University, Mathura.
INDIA.
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