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How to output the el-ph strength (g2) of coarse grid?
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Joined: Wed Apr 24, 2019 7:21 am
Posts: 2
University: TU Wien
How to output the el-ph strength (g2) of coarse grid?
Dear all,

How to output the el-ph coupling strength (g2) of coarse grids without wannier interpolation in EPW?

Referring to what has been done for “epmatf” or “epf17”, I have tried “g2_coarse=abs(sum(uf*epmatq))**2*inv_wq”, where “uf” is phonon eigenvector and “empatq” is coarse el-ph coupling matrix as said in EPW. However, the calculated g2_coarse is different from wannier interpolated values. Then what should I do to output correct values?

Wed Apr 24, 2019 8:27 am

Joined: Wed Jan 13, 2016 7:25 pm
Posts: 575
University: Oxford
Re: How to output the el-ph strength (g2) of coarse grid?
Hello,

You can try to uncomment
!write(*,*)'epmatq(:,:,2,:,nqc)**2',SUM((REAL(REAL(epmatq(:,:,2,:,nqc))))**2)+&
! SUM((REAL(AIMAG(epmatq(:,:,2,:,nqc))))**2)

inside elphon_shuffle_wrap.f90

Then also print the same elements from the variable "epmatf" in ephwann_shuffle.f90

Make sure you print g and its c.c. to avoid phase issues. You also need to average on degenerate states (average all the bands, modes and k-points). Only the average on degenerate state is expected to be the same.

Best,
Samuel

_________________
Dr. Samuel Poncé
Department of Materials
University of Oxford
Oxford OX1 3PH, UK

Tue May 14, 2019 7:37 am
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