Search found 601 matches

by sponce
Mon Oct 04, 2021 1:26 pm
Forum: Running the code
Topic: GaN-II A restart.fmt is present but not the Fepmatkqcb1 folder
Replies: 2
Views: 272

Re: GaN-II A restart.fmt is present but not the Fepmatkqcb1 folder

Dear calos818, I do agree with H. Lee that you could try using the latest tutorial on mobility from the school. However, in the particular case of the https://docs.epw-code.org/doc/GaN-II.html tutorial, it is based on the QE test-suite which means that it should be working (this is tested every nigh...
by sponce
Mon Oct 04, 2021 1:21 pm
Forum: Running the code
Topic: Mobility calculation using epw: NaN in Hole Mobility
Replies: 1
Views: 252

Re: Mobility calculation using epw: NaN in Hole 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 mob...
by sponce
Mon Oct 04, 2021 1:16 pm
Forum: General discussion
Topic: GaN-II electron mobility very low while hole mobility is ok
Replies: 2
Views: 313

Re: GaN-II electron mobility very low while hole mobility is ok

Hello, You have to adapt 'ncarrier = -1E13' to 'ncarrier = 1E13' to do electron mobility and also change the position of the Fermi level to be closer to the CBM. I could also suggest doing the more recent tutorial from the 2021 school https://epw2021.oden.utexas.edu/74-schedule scroll down that page...
by sponce
Tue Sep 14, 2021 8:48 am
Forum: General discussion
Topic: Calculation of mobility by EPW iteration
Replies: 4
Views: 1109

Re: Calculation of mobility by EPW iteration

Hello, You have to use 'int_mob = .true.' However it is not recommanded for computational reasons (more expensive that treating them separately with separate Wannierization). In addition, it the case of a large bandgap, the intrinsic carrier concentration will be very low to the point that the bisec...
by sponce
Tue Sep 14, 2021 8:40 am
Forum: Running the code
Topic: Version of EPW used in Nano Letters, 20, 8861 (2020)
Replies: 2
Views: 507

Re: Version of EPW used in Nano Letters, 20, 8861 (2020)

Dear Vahid, The version has been released in QE 6.8 and include Hall factor. Note that 2D with only 1 k/q point along the vacuum is possible in this case because it is graphene (a non polar material) and therefore no specific 2D electrostatic is needed for the Frohlich part. For 2D polar materials, ...
by sponce
Tue Sep 14, 2021 8:08 am
Forum: Running the code
Topic: Why is my xx and yy components for mobility not the same?
Replies: 1
Views: 328

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

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. ...
by sponce
Tue Sep 14, 2021 8:03 am
Forum: Running the code
Topic: Inquiry about high k point mesh for interpolation and population SR
Replies: 2
Views: 389

Re: Inquiry about high k point mesh for interpolation and population SR

Hello, Note that 2D materials are not officially supported yet in EPW. You can use the EPW input variable system_2d = .true. at your own risk (with the version QE 6.8). You will need to comment out the check in EPW/src/epw_readin.f90 In any case, your phonon should also be planar like your k-grid: n...
by sponce
Tue Sep 14, 2021 7:58 am
Forum: Running the code
Topic: Calculation in 2D semiconductor
Replies: 3
Views: 507

Re: Calculation in 2D semiconductor

Dear Marcelo Albuquerque, The mobility is independent on the carrier concentration. Therefore if you change ncarrier, the mobility should (almost) not change. If you want to look at high carrier concentration, you have to manually shift the Fermi level in the CB. You then have to redo the phonon cal...
by sponce
Tue Mar 30, 2021 8:15 am
Forum: Running the code
Topic: Questions on phonon degeneracy?
Replies: 3
Views: 599

Re: Questions on phonon degeneracy?

Dear Yaokun Ye, Thank you for your interest in EPW and welcome to the forum. It seems you are looking at the change of potential on the real-space grid (something similar to a deformation potential) and not the electron-phonon matrix element. From your Fig.1 you can see that the real part and imagin...
by sponce
Wed Mar 10, 2021 3:44 pm
Forum: Electron-phonon
Topic: questions about the BTE mobility theory
Replies: 2
Views: 874

Re: questions about the BTE mobility theory

Dear Max, Eq. 10 is the Boltzmann transport equation which is an equality in steady state between the driving force (i.e. the electric field) and the scattering (i.e. the electron-phonon scattering). If you want to understand the physics behind, I can recommand the review https://iopscience.iop.org/...