Including dynamical electronic screening in the BSE calculations

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lz dong
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Joined: Mon Jun 12, 2023 7:26 am

Including dynamical electronic screening in the BSE calculations

Post by lz dong » Mon May 06, 2024 11:15 am

Dear all,
For a system where exciton binding energy is larger or comparable than the characteristic plasmon pole energy, dynamical effects should be incorporated in the BSE calculations. See https://journals.aps.org/prb/abstract/1 ... 107.235205 (DOI: 10.1103/PhysRevB.107.235205). When I use this command to do the GW-BSE calculation (yambo -X s -r -o b -k sex -y d) by adding the scissors operator to fit the GW level (one for KfnQP_E and another for XfnQP_E), whether it includes the dynamical electronic screening in the BSE calculation? There are different approximations to numerically solve the dynamical BSE, including a static model with effective screening , the first-order perturbation approach , and exact diagonalization of the Hamiltonian. If the BSE calculation includes the dynamical electronic screening by the Yambo code, does it take an effective static screening approach when dealing with dynamical electronic screening ?

Best,
lz Dong
PhD student
Beijing Institute of Technology,China

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Daniele Varsano
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Re: Including dynamical electronic screening in the BSE calculations

Post by Daniele Varsano » Mon May 06, 2024 11:20 am

Dear lz Dong,
KfnQP_E is meant to include QP correction to the electronic band structure and does not include dynamical screening in the BSE.
At the moment, dynamical screening in the BSE is not implemented in Yambo.

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/

lz dong
Posts: 6
Joined: Mon Jun 12, 2023 7:26 am

Re: Including dynamical electronic screening in the BSE calculations

Post by lz dong » Tue May 07, 2024 4:57 pm

Daniele Varsano wrote: Mon May 06, 2024 11:20 am Dear lz Dong,
KfnQP_E is meant to include QP correction to the electronic band structure and does not include dynamical screening in the BSE.
At the moment, dynamical screening in the BSE is not implemented in Yambo.

Best,
Daniele
Thanks for your reply. If I want to compare the plasmon energy ω that control the dynamics of the screening with the exciton binding energy, does the plasmon energy refer to the PPAPntXp value we set when we do the GW calculation?

Best
lz Dong
PhD student
Beijing Institute of Technology,China

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Daniele Varsano
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Re: Including dynamical electronic screening in the BSE calculations

Post by Daniele Varsano » Thu May 09, 2024 11:30 am

Dear lz Dong,

PPAPntXp is a parameter used to model the dielectric function, and it is not the frequency of the plasmon of the system. To calculate the plasmon frequency, you need to calculate an EELS (electron energy loss) spectrum. You can do it at RPA or BSE level.

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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