Spin polarized calculation in EPW

General discussion around the EPW software

Moderator: stiwari

Post Reply
chenhanghui
Posts: 4
Joined: Wed May 09, 2018 5:56 am
Affiliation:

Spin polarized calculation in EPW

Post by chenhanghui »

Dear EPW developers,
I know from the EPW documentation that spin polarized calculations are not implemented in EPW. However, both phonon calculations and Wannier90 can handle spin polarized calculations, therefore I am wondering whether each mode-resolved electron_phonon coupling can be considered the sum of two spin contributions: i.e. lambda_{qv} = lambda_{qv}_up + lambda_{qv}_dn. Both lambda_{qv}_up and lambda_{qv}_dn are calculated using "g2" matrices for the given spin. Is this the right way to implement it or there is something fundamentally difficult that I naively missed, which prevents the implementation of spin-polarized calculations in EPW?
Thank you very much for your help.

Dr. Hanghui Chen
Department of Physics
NYU Shanghai and New York University

hlee
Posts: 415
Joined: Thu Aug 03, 2017 12:24 pm
Affiliation: The University of Texas at Austin

Re: Spin polarized calculation in EPW

Post by hlee »

Dear Dr. Hanghui Chen:

As you know, in spin-polarized calculations (nspin=2 in the QE convention; see the subroutine of set_spin_vars: https://gitlab.com/QEF/q-e/-/blob/devel ... n_vars.f90) the spin-up and the spin-down components are decoulpled. So I think that within this scheme your definition of lambda is valid.
However, both phonon calculations and Wannier90 can handle spin polarized calculations, therefore I am wondering whether each mode-resolved electron_phonon coupling can be considered the sum of two spin contributions: i.e. lambda_{qv} = lambda_{qv}_up + lambda_{qv}_dn.
I am not 100% sure, but I think that such definition is adopted in the e-ph related calculations in QE.
I know from the EPW documentation that spin polarized calculations are not implemented in EPW.
I think that there is no fundamental difficulty with implementing it as long as we are ok with the above definition of e-ph related quantities.

Sincerely,

H. Lee

chenhanghui
Posts: 4
Joined: Wed May 09, 2018 5:56 am
Affiliation:

Re: Spin polarized calculation in EPW

Post by chenhanghui »

Thank you very much, Dr. Lee.

Post Reply