Si GW corrections

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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Laura Caputo
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Joined: Sun Apr 11, 2021 3:02 pm

Si GW corrections

Post by Laura Caputo » Mon Mar 28, 2022 10:33 am

Hello,

I've been doing some calculations to calculate the band gap of Si (following the tutorial:http://www.yambo-code.org/wiki/index.php?title=Silicon) with PPA.
On the website, it seems that the k-point mesh should be converged at circa 500 k-points and 50 bands. Doing the calculation, with a 14x14x14 k point grid, I could obtain an indirect band gap of 1.11eV which should be correct for Silicon. However, when I tried to go to denser k grids like 16x16x16, I noticed that this gap becomes smaller (1.09eV) which shouldn't be correct for Si.

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Laura Caputo
Ph.D. Student
Université Catholique de Louvain
https://uclouvain.be/fr/repertoires/laura.caputo

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Daniele Varsano
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Joined: Tue Mar 17, 2009 2:23 pm
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Re: Si GW corrections

Post by Daniele Varsano » Tue Mar 29, 2022 9:24 pm

Dear Laura,

20meV I would say that is in the range of the precision of the GW method. Probably, in order to be totally confident of your results you should push also other parameters (bands, dielectric matrix size..).

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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