electron-phonon interaction

You can find here problems arising when using old releases of Yambo (< 5.0). Issues as parallelization strategy, performance issues and other technical aspects.

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

Locked
baiyunfei
Posts: 15
Joined: Thu Dec 01, 2022 12:53 pm

electron-phonon interaction

Post by baiyunfei » Mon Dec 12, 2022 2:52 pm

I am trying to follow theTutorials about el-ph interaction , I got two questions.
As is said in tutorial , I got databse of el-ph matrix . I noticed that el-ph matrix is gauge dependent, I wonder whether the gauge in el-ph matrix in database is consistent with the nscf calculation results. Apart from el-ph matrix , I also have the same question about the exciton wavefunction ,dipole matrix :are they all in the same gauge?
The second question is the Tutorials about el-ph interaction is carried out without SOC , it runs well. But when I included SOC in the calculation, I encountered a problem in DVSCF step.ph.x wil print '' el-ph coefficient calculation disabled in nocolinear/spin-oribt cases '' and stop.
What should I do to get el-ph matrix with SOC.
Yunfei Bai
Institute of Physics Chinese academy of sciences, Beijing

User avatar
palful
Posts: 56
Joined: Tue Jan 26, 2016 11:23 am
Location: Modena and Milan

Re: electron-phonon interaction

Post by palful » Tue Dec 13, 2022 9:52 am

Dear baiyunfei,

First of all may I ask you to add your signature, including affiliation, to your forum posts? It is required for posting on the Yambo forum.

The gauge for electron-phonon matrix elements is *not* consistent with the gauge of the nscf wave functions. However, all quantities involving electronic properties only are gauge-consistent.

Therefore:
nscf calculation / yambo SAVE folder / dipoles / exciton wave function ----> same gauge
electron-phonon --> not the same gauge

About el-ph calculations with SOC: this feature was disabled in Quantum Espresso v7+, so it is not a Yambo issue. It could be possible to recompile ph.x commenting the line causing the problem (found in PHonon/PH/phq_readin.f90), but you should double check that this doesn't produce wrong results!

Cheers,
Fulvio
Dr. Fulvio Paleari
S3-CNR Institute of Nanoscience and MaX Center
Modena, Italy

Locked