EPW Forum

Dear EPW users,

When I run graphene with a 500x500 k-grid, QE reduces the job to 21084 k-points in the wedge as expected. However, EPW creates a 41917 k-point wedge with the same k-grid. The issue is likely due to the use of a Gamma-centred BZ by QE versus a [0:1] k-grid by EPW. Are there any unwanted consequences with getting the grid.f90 to generate Gamma-centred k-grids particularly when mp_mesh_k is set to .true.?

Thank you,
Vahid

Vahid Askarpour
Department of Physics and Atmospheric Science
Dalhousie University
Halifax, Canada

Dear Vahid,

EPW should generate the same grid as QE. Does your system break inversion symmetry but preserve time-reversal symmetry? If so, I would suggest trying the QE development version, where this has already been implemented.

Would it be possible for you to share your input and output files? That would help me better understand the issue and provide a more accurate solution.

Regards,
Shashi

Dear Shashi,

Attached please see the EPW input files, and the epw.out file. The scattering rate includes 41917 kpoints.

Attached is also the file mesh_k output by PW/tools/kpoints.x. There are 21084 wedge points.

It is possible that the issue is related to the use of two different carbon atoms, C and C1 in order to generate the Wannier functions for a larger energy range.

Thanks,
Vahid