EPW Forum

Hello everyone,

I am running calculation to find mobility in MgTe using epw code. I have calculated mobility for 4-4-4 q points and the phonon file is also for 4-4-4 q points. The k points is in scf-16, nscf-512 total , epw1-8-8-8, epw2-8-8-8. The electron mobility is resulted in epw2.out but its scale is very high. Actually, I have done this calculation for 2-2-2 qpoints also and the mobility resulted in scale of 10^18. After increasing qpoints to 4-4-4 the scale for electron mobility is resulted in range of 10^5 cm2/Vs. How to solve this ?

Also, In epw2.out Hole mobility is showing NaN. Only electron mobility computed. I have used the tag 'int_mob = .true.' Also tried same calculation for the tag 'ncarrier = -1E13'; but still holw mobility is showing NaN in result.
int_mob = .true.
carrier = .true.
ncarrier = 1E13

Please help me with NaN error in Hole mobility and scale of electron mobility.

Dear Maitryj,

A NaN in electron or hole mobility often results from the fact that your Fermi level is incorrectly set (fermi_energy) such that the Fermi level +- 'fsthick' value will fall within the bandgap.

If this is the case, then there are no states that you are considering and therefore the mobility is NaN.

Make sure that your Fermi level is positioned close to the VBM or CBM (depending if you want electron or hole mobility) and that fsthick is large enough.

Hope this helps,
Sam