[Pw_forum] electron-phonon coupling at a certain k point

[Tiju Thomas]

Dear Profs  Giannozzi, Gironcoli,Corso, Baroni , and pw users

I need to calculate the electron-phonon coupling for phonons in my system
only along certain directions, that is for the phonons having definite q
values.

 Hence I do'nt need to calculate the electron-phonon coupling for all the
phonons. Is there a prescription that you can suggest to do this in the
fastest manner (without doing the dense q point calculation suggested in
example 7 for phonons (input to ph.x there uses a 4*4*4 q point mesh
which will be very expensive for me), since I will need electron-phonon
coupling only along some directions. Most computational effort will go a
waste since I will not use the data on electron-phonon coupling at most
of the points).

For getting the electron-phonon coupling, I realize that in the electronic
scf step- the k point mesh needed should be very dense in this case, but
the kpoint step involving ph.x is very time consuming, so may be I could
just mention the q points in particular and get the information on
electron-phonon coupling, but if I do that do I get accurate results?

Thanking you in anticipation,

Yours faithfully,
Tiju Thomas
MS
Bangalore