electron-phonon interaction

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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

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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.

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!

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