EPW Forum

Dear all, I am facing a weird problem when calculating the spectral function for graphene. I have first converged the line-width of the electrons which works fine at an nscf-mesh of 33x33x1 and a q-point mesh of 11x11x1. I interpolate at a fine q mesh of 500x500x1 which gives very nice smooth linewi...

Dear all, for the spectral function the self-energy is taken as diagonal in nn'. Giustino's El-Ph paper notes that [...] we are considering for simplicity non-degenerate electronic states, and making the assumption that the off-diagonal elements of the self-energy can be neglected. In more general s...

Hi all, I have a short question. I realize when I have a gapped system and put the Fermi level in the gap the phonon self energy (linewidth) is zero, which, as I read in another thread, is due to the two delta-functions which, I think, is also referred to here: m The final expression is positive def...

Just saw it, thanks Samuel!

Hi Andrei, good (bad?) to know you experienced a similar behaviour, means it is not my fault entirely I will check if the dvscf differ significantly and I am running the job again using dipfield instead (which apparently does not work properly in ph.x according to the mailing list but oh well...)! I...

Dear all, has anyone tested the new compatibility of the new assume_isolated='2D' in QE 6.2.1 and EPW? I get very nice phonon and electronic bands (for a single layer MgO) but unfortunately the Im electron selfenergy seems fairly high (~2-3 times compared to bulk). Maybe someone could shed some ligh...

Than you for the swift and reassuring reply, sometimes I get overly paranoid about what the code is doing when I am not watching... With regard to 2D systems, do you have any recommendation which parameters to increase first when trying to converge? Above input gives me too high Im(Sigma) (2-3 order...

Hi all, just a quick question: is it normal that the fermi level on the coarse grid is always reported as 0.0 eV? I wannierize all bands (no bands skipped) and the fermi level on the fine grid is calculated properly (it is the same as the "highest occupied level" from the nscf run), but in...

Hi Carla,

sorry for the late reply but the answer is "yes". Seems with an ibrav that is NOT 0 it works well! Great example in the School2018 material, was fun to work through that as well!

Best,
Chris

Dear all, I greatly appreciate the direct output of the El-Ph matrix element, a very useful addition to the code! I was wondering which exactly is the quantity printed with respect to the equations shown on m (I only calculated it for Gamma point as suggested in the manual) Electron-phonon vertex |g...