[QE-developers] interpolation scheme in the el-ph in PHonon code

[Nadeem Muhammad]

Dear

I am Muhammad Nadeem, a master degree student in department of physics at
Sungkyunkwan University South Korea. I am working on el-ph calculation of
alkali doped organic superconductor. I am using Quantum Espresso code for
that. I have some trouble while using *electron_phonon='interpolated'* in
PHonon package. As you can expect that my system is quite large and when I
use this interpolation routine even with 2x2x2 q-points and 4x4x4 k-points
it gets stuck at electron-phonon stage. My calculation goes very well If I
use *electron_phonon='simple'.* I am using *ibrav=0.  *Is this happening
because interpolation routine does not work in parallel on multiple cpu? Is
there some remedy for my problem with this interpolation scheme. As you can
expect I can't go for very high number of q-points for dfpt calculation and
hence my double delta integration for electron-phonon vertices converges at
very high smearing (degauss=0.4Ry) if I use electron_phonon='simple'.
Interpolation is the only option left for my calculation. Please give some
comments on smearing too. As I understand that this is broadening over
electron bands around fermi level so 0.4Ry=5.4eV is too large to give
physical electron-phonon coupling parameter. Is it true? if so then please
suggest me some solution to tackle this issue.

Looking forward to listen your comments on this issue. Thank you for your
time.

Best Regards
Nadeem
-- 

*Muhammad Nadeem*

*Graduate Student*

*Department of Physics Sungkyunkwan University, Suwon*
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