Doubt about the number of bands included in scf calculation

[AnishDas-2025]

Dear experts,

I have a little doubt. I was going through the Si example given with the code. There I saw that in the scf calculation of the phonon, nbnd is set to be 8 (nbnd=8), which is basically the number of wannier centres used in wannierisation (sp3 for two si atoms in the unit cell. In epw it is nbndsub=8). Is it mandatory to set nbnd in scf while doing the phonon?? We generally don't do scf and phonon thereafter with the fixed nbnd. So, is it necessary to fix the nbnd (or the number of wannier centres) in the scf from the 1st step? I am dealing with metals. I have no doubt about the nbnd in the nscf step.
Thank you in advance
Anish

[nakib]

Dear Anish,

Thank you for your question.

"So, is it necessary to fix the nbnd (or the number of wannier centres) in the scf from the 1st step?"

I don't think it is.

By the way, if you have questions related to QE/Wannier90/EPW, I think the forums of those codes would be the best place to get answers. We only focus on the transport side of things.

Best,
N.

[AnishDas-2025]

Dear Dr. Nakib,

Thank you for your response. I checked both with and without nbnd. It does not have any impact.

Thank you
Anish