EPW Forum

Dear EPW developer, When we solve the isotropic Eliashberg equation, we recently found that at a given temperature, the gap value strongly depends on the cutoff of imaginary Matsubara frequency. For a particular example, at a given temperature (T = 0.5 K), the gap is equal to 0.14 meV when "wscut ...

Dear Roxana, I just have a quick question following the previous thread "Testing USPP vs NC: electron-phonon matrix elements". You mentioned that "I updated the USPP implementation in EPW and the corrections were made available in the QE developer branch on gitlab.". I now downloaded the latest ...

Dear Roxana, Thank you very much indeed. I am sorry that I have been dwelling on this issue. I know the subroutine to calculate a2fij(ik,iq,ibnd,jbnd,iwph). It is a power subroutine, but it contains too much information (k- and q- dependence). Therefore I decided to implement band-resolved "a2f ...

Dear EPW developers and EPW experts, I notice that in EPW, there are two different ways implemented to calculate "a2f" function. One is to set "eliashberg = .true." and "liso = .false. & laniso = .false.". The subroutine evaluate_a2f_lambda generates a "PREFIX.a2f" file. The other is to set "a2f ...

Dear Roxana,
Thank you very much.

Dr. Hanghui Chen
NYU Shanghai and New York University

Dear EPW developers, I am wondering whether the current implementation of EPW enables users to solve two-band (or even multi-band) isotropic Eliashberg equation. So far if we provide a total "a2f" file, a "one-band" isotropic Eliashberg equation is solved (one Z and one Delta). Is it possible that ...

Dear EPW developers, The reference PRB 87, 024505 (2013) says that in the implementation of EPW, the el-ph self-energy is assumed to be diagonal in band indices. Does this approximation break down for systems with multiple-degenerate bands at the Fermi level? For example, a simple cubic perovskite ...

Dear Roxana,
I increase the lowest temperature and it works now.
Thank you very much for your help. I greatly appreciate that.

Dr. Hanghui Chen
New York University Shanghai and New York University

Dear EPW developers, I am running a calculation of isotropic Eliashberg equation + Pade approximation (given *a2f file). The calculation of isotropic Eliashberg equation is successful but the Pade approximation crashes. The error message is: Program received signal SIGSEGV: Segmentation fault ...

Dear Roxana,
Thank you very much indeed. Your answer is helpful.

Dr. Hanghui Chen