BSE calculation- dense k-grid

Deals with issues related to computation of optical spectra, in RPA (-o c) or by solving the Bethe-Salpeter equation (-o b). Includes local field effects, excitons, etc.

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

Post Reply
pyadav
Posts: 5
Joined: Thu Nov 26, 2020 2:56 pm
Contact:

BSE calculation- dense k-grid

Post by pyadav » Thu Jan 14, 2021 11:37 am

Dear Developers,

Can someone please help me with doing BSE calculation using a very dense k-grid, like 51x51x1 while keeping the DFT k-grid low (12x12x1)? There is a paper that has mentioned YAMBO for this purpose (PHYSICAL REVIEW B 88, 045412 (2013).

Wishes,
Pushpendra
Pushpendra Yadav
Ph.D. Research Scholar
Quantum Transport and Theory Group
Department of Physics
Indian Instittute of Technology Kanpur, India.

https://sites.google.com/site/amitkag1/

User avatar
Daniele Varsano
Posts: 2604
Joined: Tue Mar 17, 2009 2:23 pm
Contact:

Re: BSE calculation- dense k-grid

Post by Daniele Varsano » Thu Jan 14, 2021 11:47 am

Dear Pushpendra,
I may be wrong, but in the paper you mention a large grid (51x51x1) is used.
Can you explain better what you mean by keeping the DFT k-grid low (12x12x1)?

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/

pyadav
Posts: 5
Joined: Thu Nov 26, 2020 2:56 pm
Contact:

Re: BSE calculation- dense k-grid

Post by pyadav » Thu Jan 14, 2021 12:38 pm

Dear Dr. Daniele,

Maybe I misunderstood the paper mentioned above but I wanted to understand that suppose we do a ground-state calculation (scf/nscf) for k-grid 12x12x1 and use these ground state wave-functions to do the G0W0 calculation. Now if I want to calculate BSE spectra for a higher k-grid (say 51x51x1). For this hogher k-grid BSE calculation do I need to go back to DFT calculation with higher k-grid or is it possible to implement higher k-grid in YAMBO?

Thank you!
Last edited by pyadav on Thu Jan 14, 2021 1:21 pm, edited 1 time in total.
Pushpendra Yadav
Ph.D. Research Scholar
Quantum Transport and Theory Group
Department of Physics
Indian Instittute of Technology Kanpur, India.

https://sites.google.com/site/amitkag1/

User avatar
Daniele Varsano
Posts: 2604
Joined: Tue Mar 17, 2009 2:23 pm
Contact:

Re: BSE calculation- dense k-grid

Post by Daniele Varsano » Thu Jan 14, 2021 12:39 pm

Dear Pushpendra,
yes, you need to recalculate the electronic structure for a denser grid, as you need it to build your BSE matrix.

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/

pyadav
Posts: 5
Joined: Thu Nov 26, 2020 2:56 pm
Contact:

Re: BSE calculation- dense k-grid

Post by pyadav » Thu Jan 14, 2021 1:24 pm

Thank you, Dr. Daniele, for the clarification.
Pushpendra Yadav
Ph.D. Research Scholar
Quantum Transport and Theory Group
Department of Physics
Indian Instittute of Technology Kanpur, India.

https://sites.google.com/site/amitkag1/

Post Reply