[Wannier] Nb Phonon and Electron Band oscillatory Wannier Interpolation

[Bander Linjawi]

Dear All,

As part of EPW calculations of the EPI matrix lambda on Nb, I am obtaining oscillatory wannier interpolation of both the phonon and electron band structures.

I'm sharing two plots of PW vs Wannier phonon and Fermi-crossing electron bands. For the interpolation, an nscf calculation on a K-Mesh of 10^3 was used to generate .nnkp file. The scf calculations had the same settings except a K-Mesh of 20^3 was used, and the phonons a Q-Mesh of 10^3. It is possible that I need to increase the nscf K-mesh for finer interpolation, but since I'm using Wannier 3.1 with the tag use_ws_distance = .true. by default, I thought it might help. Additionally, whenever I try to wannier interpolate through epw.x on multiple nodes, I run into this parallelization error:


Error in routine epw_readin (1):

     Number of processes must be equal to product of number of pools and

     number of images

     Image parallelization can be used only in calculations on coarse grid.

I would like to interpolate only the two bands the cross the Fermi-level, out of the 11 in the pseudopotential I used. Is that possible? Or would I need to interpolate more bands and freeze the Fermi-crossing ones? If so, I am not sure how to specify the projections, and suggestions are greatly appreciated. I am currently using the auto-scdm projection scheme and interpolating all 11 bands.

Below are the versions used for this calculation, as well as the google drive folder for the phonon and electron band plots and input/output files. nb.epw1.in is the input for wannier interpolation with epw.x.

Versions:
QE: 6.8
EPW: 5.4.1
Wannier90: 3.1

https://drive.google.com/drive/folders/1I-rnjZFgS3BDttcFLnOFKd9RUxar86Q3?usp=sharing

Thank you,
Bander Linjawi
PhD Student Mechanical Engineering
Duke University
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