GW calculation in 3.2.5-rev26 vs 3.2.5-rev34

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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soh
Posts: 4
Joined: Wed Nov 14, 2012 1:33 pm

GW calculation in 3.2.5-rev26 vs 3.2.5-rev34

Post by soh » Mon Apr 08, 2013 10:57 am

Hi,

I recently installed yambo 3.2.5-rev34 and had been previously using 3.2.5-rev26. I wanted to test the yambo -g n -p p calculation for a two atom Si cell. However the GW shift to the eigenvalues was wildly different for the same input files. Upon inspection the only difference in the report files was this:

rev 26
< Green`s function energies :Perdew & Zunger (xc)
< wavefunctions :Perdew & Zunger (xc)
< PPA diel. fun. energies :Perdew & Zunger (xc)
< wavefunctions :Perdew & Zunger (xc)
---
rev 34
> Green`s function energies :+Vosko, Wilk & Nusair (parametrization of the RPA energy)(C)
> wavefunctions :+Vosko, Wilk & Nusair (parametrization of the RPA energy)(C)
> PPA diel. fun. energies :+Vosko, Wilk & Nusair (parametrization of the RPA energy)(C)
> wavefunctions :+Vosko, Wilk & Nusair (parametrization of the RPA energy)(C)

I've attached yambo.in (which was generated with yambo -g n -p p), r_HF_and_locXC_em1d_ppa_gw0 and o.qp for both calculations. Is there some additional flag needed with rev 34 in yambo.in?

Many thanks,
Siobhan

Siobhan O'Halloran
PhD Student
Materials Theory Group
Tyndall National Institute
Cork
Ireland
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Daniele Varsano
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Re: GW calculation in 3.2.5-rev26 vs 3.2.5-rev34

Post by Daniele Varsano » Mon Apr 08, 2013 11:14 am

Dear Siobhan,
this happens because you are using a new revision with old database. The new revision does not read the previous databases correctly
and produce not reliable results. The Vosko, Wilk & Nusai you read in the report is a nonsense caused by the wrong reading of the database.
This is something we will fix soon. The problem is solved by producing all the database with the same revision of the code.
Cheers,

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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