[QE-users] Fwd: problem in band gap

[Giuseppe Mattioli]

Dear Neelam Swarnkar
What do you mean when you say "correct band gap"? A literature  
experimental value? A literature calculated value? In the former case,  
the compatibility depends on the exchange-correlation functional you  
use. There is plenty of literature on this, you just have to type "DFT  
underestimation band gap" in google to have an idea. In the latter  
case, if you are trying to reproduce the results of previous  
theoretical calculations, then you must use the same theoretical setup  
in a proper way, and it is impossible to help you if you don't post  
relevant information (QE version, input, ...)
HTH
Giuseppe

Quoting Neelam Swarnkar <neelamswarnkar35 at gmail.com>:

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> From: <users-owner at lists.quantum-espresso.org>
> Date: Wed, May 6, 2020, 3:25 PM
> Subject: problem in band gap
> To: <neelamswarnkar35 at gmail.com>
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> ---------- Forwarded message ----------
> From: Neelam Swarnkar <neelamswarnkar35 at gmail.com>
> To: users at lists.quantum-espresso.org
> Cc:
> Bcc:
> Date: Wed, 6 May 2020 15:24:49 +0530
> Subject: problem in band gap
> Dear All
>
> I am new for using quantum espresso-6.3. i am calculating the scf ,nscf,
> bands, etc of ZnSb thermoelectric material this material belongs to Pbca
> (61) space group. and had orthorhombic crystal structure , no of electrons
> =8.
>
>
> I have done scf, nscf calculation and band calculation but not found the
> correct band gap.
>
> I don't know what wrong in this , or may be choose wrong psedopotential.
>
> please explain to me  , correct way to calculate correct band gap.
> Zn.in    and Zn.out is my scf calculation.
>
> QE-user
> Neelam Swarnkar
> Phd scholar



GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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E-mail: <giuseppe.mattioli at ism.cnr.it>