Why is my xx and yy components for mobility not the same?

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jhosamelly
Posts: 6
Joined: Wed Jul 21, 2021 8:12 am
Affiliation: DLSU

Why is my xx and yy components for mobility not the same?

Post by jhosamelly »

Hello everyone!

I am doing electron mobility calculations of MoS2.
Here's the link to relevant output and input files https://drive.google.com/drive/folders/ ... sp=sharing .

I was just wondering why in my result, the xx and yy components of the electron mobility matrix are not the same or even close?

Here's the last iteration of the electron mobility calculation (BTE).

Code: Select all

     Iteration number:        64

     =============================================================================================
       Temp     Fermi   Elec density  Population SR                  Elec mobility 
        [K]      [eV]     [cm^-3]      [e per cell]                    [cm^2/Vs]
     =============================================================================================

      300.000   1.3143   0.10000E+14  -0.27326E-03    0.954901E+03   -0.205235E+03   -0.489098E+02
                                                     -0.205235E+03    0.119189E+04   -0.282381E+02
                                                      0.308233E+02    0.177958E+02    0.326700E+04

                                                      0.853689E-06    Max error
      
Based on this https://docs.epw-code.org/doc/GaN-II.html tutorial, that is the in-plane electron mobility.

Thank you to anyone who would clarify.

sponce
Site Admin
Posts: 601
Joined: Wed Jan 13, 2016 7:25 pm
Affiliation: EPFL

Re: Why is my xx and yy components for mobility not the same?

Post by sponce »

Hello,

The non-zero population indicates a problem such that the results cannot be trusted.
This is likely due to your 4x4x4 q-point grid instead of 4x4x1.

Before doing mobility calculation, you need to make sure that the electronic bandstructure and phonon bandstructure are correctly interpolated.
You can plot them by using the EPW input variable

Code: Select all

 band_plot   = .true. 
and provide the corresponding filqf and filkf file along high symmetry path. Make sure you get the same bandstructure as direct NSCF calculation with QE or phonon dispersion using matdyn.x
If this is not the case, then you Wannierization is not good.

Best wishes,
Samuel
Dr. Samuel Poncé
Institute of Materials
École Polytechnique Fédérale de Lausanne (EPFL)
Switzerland
Web: https://www.samuelponce.com

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