EPW Forum

Hi Zeeshan, You can generate the homogeneous coarse grid for the nscf calculations using a script 'kmesh.pl' from wannier90 community, please check inside wannier90-3.1.0/utility or https://github.com/wannier-developers/wannier90/blob/develop/utility/kmesh.pl For example; if you want to use 8x8x8 me...

Hi dhw, You need to do convergence tests for few values of fsthick. You can start from 4 times the maximum phonon frequency of your system (many times I have found we do not need to go beyond). For example, in MgB2, the maximum phonon frequency is around 100 meV, so we have used fsthick = 0.4 eV, wh...

Hi DSC, The "Missing Key" appears because you do not have data for that specific k-point. Is your nscf calculation correctly done with nsym = .true. flag? If you want to use EPW to plot Fermi surface (and color gap on this), a new implementation is available in EPW. For this, use "fermi_plot = .true...

Hi dhw, A few meV difference in Fermi energies calculated in coarse grid (nscf run) and fine mesh (epw run) is expected (because of different k-meshes used). If you want to compare the Fermi energies between pw and epw calculation, you need to make a test nscf calculation on the same mesh that you h...

Hi zhongcy, I think it is not possible to show the color scale on the side of your FS plot in a single plot. However you can use the color scale from 2D Data Display. For this go to; Utilities/2D Data Display ... click Slice and then OK. The color scale correspond to your main plot. Export the image...

Hi dhw, It looks like you do not have enough Matsubara points in the Pade continuation. I am not sure which version of the code you are using, if it is the latest version, we have introduced a new input variable 'npade', see below; https://gitlab.com/QEF/q-e/-/blob/develop/EPW/src/epw_readin.f90#L26...

Hi Zegnet,

This type of errors occur usually because of not enough memory per core. It would be great if you could give more about your input, output, and run (how many cores?) files.

Happy EPWing,
Hari

Hi Roman, I have one more question, out of curiosity: I noticed that the epwwrite quantities (epwdata.fmt and XX.epmatwpX) are actually not rewritten in that setting and the EPW std-output claims regular mode instead of "RESTART", so I wonder which other flag(s) determine this behaviour? Or is it re...

Hi Chill, I can only guess, this may be because your 'dvscf*' files are not correctly written. Could you check their sizes? Are all the same? Did you have to restart your phonon or you did in a single run? I am asking this because I had the same issue long back when I restarted my phonon for a q-poi...

Hi Ilias,

Yes you are right, it should be " wannierize = .false.", which I just corrected it.

Do you have "B3S.ephmat" directory where you can see ephmatXX (pool index), ikmap, egnv, freq files?

It would be nice if you could share your full output file.

Happy EPWing,
Hari