GW calculation for a 2D metallic system

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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8813204602
Posts: 58
Joined: Tue Jun 15, 2021 5:53 pm

GW calculation for a 2D metallic system

Post by 8813204602 » Sun Aug 01, 2021 7:30 pm

Dear Yambo developers and users

1. Dose Yambo support the G0W0 calculation for 2D metallic or half-metallic systems for example transition-metal dichalcogenides (including d valence orbitals)? Doesn't discontinuity of the band occupation crossing the fermi surface in these systems cause a problem in Yambo GW calculations?
2. Are the GW calculations for metallic and half-metallic systems (including d valence orbitals) the same as for semiconductor systems or need to consider other technical issue or additional input variable?
3. Can you please introduce an article that did GW calculation for a 2D metal or half-metal by Yambo?

Thanks a lot

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Daniele Varsano
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Re: GW calculation for a 2D metallic system

Post by Daniele Varsano » Mon Aug 02, 2021 7:42 am

Dear anonymous user,
please sign your post with your full name and affiliation, this is a rule of the forum.

You can perform GW calculation for these systems, anyway at the moment the Drude term it is not included in the screening.
This makes the calculation harder to converge with respect the k point grid.
We are working on the inclusion of the metallicity in the screening for 2D system, at the moment this development it is not yet available, and it will be hopefully available soon and this will allow to accelerate the convergence with respect the k points.

You need to perform the calculation as usual, Yambo will take care of the fractional occupation number across the Fermi level, there is not discontinuity assuming you use a smearing in your ground state calculation. But again, the convergence wrt the k points could be very hard!

In this paper you can find a GW calculation of a metallic 1D system (Phys. Rev. B 101, 161410(R)), in this case the metallicity was treated with an ad-hoc implementation for the BSE kernel, but not for the GW part (see support. info.).

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/

8813204602
Posts: 58
Joined: Tue Jun 15, 2021 5:53 pm

Re: GW calculation for a 2D metallic system

Post by 8813204602 » Tue Aug 03, 2021 4:40 pm

Dear Daniele

Thank you very much for your quick reply.
Mitra Helmi,Ph.D student
Ferdowsi university of Mashhad
Mashhad,Iran

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