EPW Forum

Dear Agathyan,

To me it seems that the two dispersions are plotted on different q-paths. Take a look at the q point coordinates inside the phband.freq and si.freq files, perhaps this helps explain the difference?

Best,

Nina.

Hello, Correct me if I am wrong, but it seems that the issue is related with the interpolated phonon frequencies, and not with the phonon self-energy calculation. Did you run the quadrupole EPW calculation as the initial calculation, with flags: epwwrite = .true. wannierize = .true. or did you run ...

Dear Nikhitha, Does your system have 100 bands in total? If yes, would you like to wannierize all of those bands? If not, then with the flag 'bands_skipped' you can explicitly exclude the bands that are not among these 100 ones. On the other hand, 100 bands is really a lot, and you subsequent ...

Dear Nikhitha, Yes, the wannierization procedure fails in this case - the spreads are very large: Wannier Function centers (cartesian, alat) and spreads (ang): ( 0.76356 0.00189 -0.00963) : ******** As a first step, could you try the same wannierization (if you are sure that the initial projections ...

Dear Jack,

Correct!

Best,

Nina.

Dear Mab! Ingredients to obtain the Allen-Dynes Tc (electron-phonon coupling constant \lambda and the logarithmic frequency w_log) are both calculated from the Elishberg spectral function. You could compare the Eliashberg spectral function obtained using the two choices of fsthick, because this ...

Dear Jack,

Could you try setting 'longrange_only = .true.' ?
At the EPW website there might be a mistake regarding that variable.

Best,

Nina.

Dear Ilias,

I am not sure and I might be overlooking something, but to me it seems like the only possibility would be to manually select the bands which enter the α²F(ω) calculation..
The orbital character of the bands can be calculated with projwfc.x from QE, for example.

Best regards,

Nina.

Dear Mab, The electron coupling constant of about 0.3 and a large w_log (65 meV) indeed lead to a small Tc according to the Allen-Dynes expression. However, as I understand from your input file, you would like to calculate the Tc using the anisotropic Eliashberg equations, right? In this formalism ...

Hello!

To me everything looks fine now. I would recommend checking the convergence of the matrix elements. The grids might be too coarse. Would it be possible to increase the k/q grids and repeat the calculations?

Best regards,

Nina.