[Pw_forum] problem in calculating graphen dos

[Giovanni Cantele]

On Oct 31, 2013, at 10:17 AM, ehsan targholi <targholi at gmail.com> wrote:

> hi
> i calculate dos of graphene. but the result of it not coincident with reference . my input for dos calculation is:
> 
> &dos
>   prefix='gs24'
>   outdir='/home/ehsan/espresso-5.0/tmp/'
>   fildos='gs24.dos',
>   Emin=-25.0, Emax=25.0, DeltaE=0.1
> /
> 
> 
> and result is attached. so as you see in the attached picture, the positive region of my calculation have not any peak but the reference of graphene dos have peak. pleas guide me
> 
> have a good day
> ehsan targholi
> <dos.jpg>_______________________________________________
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The input for nscf would be more explicative, since the dos.x run is just a post-processing of the data produced at the
pw.x level.

However, it seems to me that:
1) you did not include "empty" bands, so you obtain zero DOS at E > 0
2) you did not run, after self-consistency, a non self-consistent calculation with a much denser k-point grid. Indeed, the
"irregular" shape of the DOS (with so many "unphysical" peaks) usually comes from an insufficient sampling of
the Brillouin zone. What you should do is to increase the k-point grid with respect to self-consistency
(try for example, 8x8x1, 12x12x1, 24x24x1, …. to see how the resulting DOS changes) until the result is converged.

Giovanni


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Giovanni Cantele, PhD
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