Extracting static bare susceptibility

[dlnguyen]

Dear all,

I am interested in calculating the static bare susceptibility \chi(q) = 2/N_k \sum_{knm} \frac{f_{k+qn}-f_{km}}{\epsilon_{k+qn}-\epsilon_{km}}
If I understand correctly, the \chi(q) is electron-phonon contribution to the static phonon self-energy assuming constant matrix element.
Does EPW supports to extract this values as a function of q?
Is that correct that I should print out the phonon self-energy when the g^2 =1 to obtain \chi(q)?
I appreciate any suggestions that you could give.

Best,
Duc-Long
Graduate student, Taiwan

[sponce]

Dear Duc-Long,

What you refer to can be accessed through the nesting function flag of EPW: http://epw.org.uk/Documentation/Inputs#nest_fn

However this will give you the electronic nesting function, not the phononic one.

You can modify the selfen_phon.f90 routine and put by hand g = 1 there.

Best,

Samuel