EPW Forum

Dear Experts,
I have done my nscf with 16x16x1 grid and the file shows all the eigenvalues are fully converged.My DFT band structure agrees with wannier band structure except a small gap at K point which is unphysical.I have enclosed the wannier band here: https://ibb.co/k715MU .
1.How can I resolved this gap?
2.Do I need to introduce any other wannier parameters to obtain full convergence.
3.Is there anything else which can be done here to remove this problem because 16x16x1 nscf grid is good and I don't think the enhancement of this grid with reduce this issue,this is because of something else.

Please help.

Thanks and regards,
Anindya Bose

Dear Anindya,

I have never studied graphene myself but based on the literature and on some old posts on this forum (see e.g. viewtopic.php?f=3&t=367&start=0&hilit=graphene ) it looks like you might need a 24x24x1 k grid for the wannierization. This is not because your DFT bands are not converged, but because an accurate wannier interpolation in this system needs a rather dense k grid.

Best,
Carla