Convergence and Bandstructure with GW correction

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)

Moderators: Davide Sangalli, andrea.ferretti, myrta gruning, andrea marini, Daniele Varsano

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Daniele Varsano
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Re: Convergence and Bandstructure with GW correction

Post by Daniele Varsano » Mon Sep 22, 2014 6:14 pm

Dear Rupesh,
there could be plenty of reason for the disagreement with the literature (structure, ground state quality, convergence parameter, etc....).
There are plenty of GW calculations in the literature on this system you can compare with, it is up to you to try to understand what is going on.
You can find some example here :
http://arxiv.org/pdf/cond-mat/0307181v1.pdf
By the way, did you check carefully the convergences of all parameters entering in a GW calculation? In the above papers, for instances, much more G vectors were used for the screening and exchange part of the self energies.

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/

rupesh
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Re: Convergence and Bandstructure with GW correction

Post by rupesh » Mon Sep 29, 2014 6:24 am

Dear Daniele,

I got the correct G0W0 band structure for material (GaAs, Diamond). I want to know the dielectric matrix or dielectric constant for screened potential used in my calculations , How do I find it ? Is it possible to know it explicitly ?

Thank you !!

Regards,
Rupesh
Rupesh Chaudhari,
Senior Undergraduate,
Engineering Physics,
IIT Bombay, India

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Daniele Varsano
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Re: Convergence and Bandstructure with GW correction

Post by Daniele Varsano » Tue Sep 30, 2014 5:01 am

Dear Rupesh,
the dielectric matrix used in the screening is calculated at RPA level. You can have the macroscopic quantity by doing an RPA calculation (optics).

Code: Select all

yambo -o c ..
The dielectric matrix is a big object and it is not reported explicitly.
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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