GW band gap same with PBE

Concerns issues with computing quasiparticle corrections to the DFT eigenvalues - i.e., the self-energy within the GW approximation (-g n), or considering the Hartree-Fock exchange only (-x)

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Daniele Varsano
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Re: GW band gap same with PBE

Post by Daniele Varsano » Mon May 27, 2019 1:24 pm

Dear Burak,
hard to say what is going on, you have a quite strange path, and most importantly I've seen in your GW input:

Code: Select all

% GbndRnge
15 | 25 | # [GW] G[W] bands range
%
this is very dangerous because of the lack of completeness in the GW summation: this should start for band 1 and then bands should be added until convergence.
It is then possible that you have inconsistent corrections among bands providing inconsistent corrections among bands giving problems in the search of the Fermi level after the corrections are applied.
Anyway, without looking at the report I cannot say much as I do not know the entity of the corrections, the number of occupied states etc.

Best,

Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

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