[Pw_forum] band gap at Gamma point in primitive cell different from the band gap at Gamma point in conventional cell

[xirainbow]

Your condition is normal.
The Brillouin zone folding must change the electronic gap.

On Mon, Oct 6, 2014 at 11:15 AM, Juliana Morbec <jmmorbec at gmail.com> wrote:
> Dear All.
>
> I have tried to calculate the band gap of Ta3N5. When I use the primitive
> cell with 16 atoms I obtain a band gap of 1.68 eV at the Gamma point;
> however, when I use the conventional cell with 32 atoms, I find a band gap
> of 1.34 eV at the Gamma point. I have already checked the convergence of
> both calculations with respect to the energy cutoff and the k-point grid.
>
> I was wondering if this could be related to the Brillouin zone folding. Do
> anyone have any idea why I obtain too different values at the same point?
>
> I will really appreciate any help in this issue.
>
> Best wishes,
>
> Juliana Morbec
> -----
> Juliana M. Morbec, Ph.D.
> Postdoctoral Researcher
> Institute for Molecular Engineering, The University of Chicago
>
>
>
>
>
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-- 
____________________________________
Hui Wang
School of physics, Henan University of Science and Technology, Henan, China