[QE-users] Relevance of electron-phonon at Gamma only for defects in bulk

[JAY Antoine]

Dear community, 
I need to calculate the electron-phonons matrix elements of a simple defect in a bulk materials.
I use a super cell that is large enough to study the system at gamma only:
- For the scf: k=gamma and k=2^3 give the same total energies (+/- 1 meV/at).
- For the phonons: q=gamma and q=2^3 give the same ph-DOS (after interpolations).

However, reading the el-ph documentation and examples,
it is suggested that these two steps must be done on a dense k-points and q-points grids.

Has this suggestion been done only for simple cells? (and is then not necessary for huge super cells...)

Any comment would be apreciated,
Best regards,

Antoine Jay
 
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