[Pw_forum] Supercell in GWW calculations

[Geoffrey Stenuit]

Dear S.D. Wang,

It depends on what you are computing: molecule or periodic system. For  
a molecule, as you know, the answer is a 1x1x1 sc with enough vacuum  
around it. For a periodic system, it depends on the size of the cell  
in the real space.

Anyway for both cases, the GWW code computes only the GWW eigenvalues  
at the gamma point. Nevertheless, a 2X2X2 or 3x3x3 or beyond sc should  
be used for improving the accuracy of the exchange part of the  
eigenvalues.

For more informations, please have a look on your webpage (tutorial part)
http://gww.qe-forge.org/index.php?page=tutorial

Hope it helps,

Joe

Quoting shudong wang <sd.wang000 at gmail.com>:

> Dear developers:
> I confused about the size of supercell in GWW calculations. What the
> supercell should I use,2x2x2 or 3x3x3 ....? Does it must be used in the GWW?
>
>
> Thanks in advance!
>
> S. D. Wang
>



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