[Pw_forum] a question about electron-phonon coupling

[Paolo Giannozzi]

On Sep 29, 2006, at 13:31 , li quan wrote:

> Dear Polo,
>    Thanks for your and others' answers, you say that
> >electron-phonon coefficients are seto to zero
> > for phonons whose frequency is smaller than 20 cm^-1
>
> But, if I want to get the value of electron-phonon coefficients for  
> phonons whose frequency is smaller than 20 cm^-1. What should I do?  
> Could I reduce the value of "eps"?

the idea behind the cutoff at 20 cm^-1 is to get rid of acoustic phonons
at q=0 (whose contribution to the el-ph coupling is zero anyway).
If you have "real" phonons with frequency < 20 cm^-1 , you may try
to reduce the value of eps, but I guess it will be hard to get an
accurate value.

Paolo