[Pw_forum] electron-phonon matrix element - relationship between npert and nu

[Hua Bao]

Dear Paolo and QE-users,

The electron-phonon matrix element is written in terms of ibnd, jbnd, ik,
ipert+imode0. (in elphon file)
Based on your discussion with Ajit, I realize that ipert is the number of
perturbations.

However, I am still having difficulty to project nirr/npert to a specific
\nu. It can be easily understand they are related, though.

For a phonon wave vector q, there are \nu phonon modes. These modes are
categorized into nirr irreducible representations, and each nirr has npert
perturbations? Can I assume one perturbation is a component of one phonon
pattern?

Would you please point out the relationship between npert and \nu?

Thanks,
Hua
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