Epw BZ related error

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anindya@iiita
Posts: 75
Joined: Sat Mar 03, 2018 7:37 am
Affiliation:

Epw BZ related error

Post by anindya@iiita »

Dear Sir,
I am getting the following error while running epw.in and calculation is stopped,
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine epw_setup (1):
coarse k-mesh needs to be strictly positive in 1st BZ
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Please suggest me how to resolve it.

Regards,
Anindya Bose
JRF.IIITA

sponce
Site Admin
Posts: 616
Joined: Wed Jan 13, 2016 7:25 pm
Affiliation: EPFL

Re: Epw BZ related error

Post by sponce »

Dear anindya@iiita,

You have to specify by hand the homogeneous coarse grid for the nscf calculations before the epw calculation.

The grid must be between 0-1 (and not between -0.5 and 0.5).

Best wishes,
Samuel
Prof. Samuel Poncé
Chercheur qualifié F.R.S.-FNRS / Professeur UCLouvain
Institute of Condensed Matter and Nanosciences
UCLouvain, Belgium
Web: https://www.samuelponce.com

azeeshan
Posts: 2
Joined: Mon Jun 28, 2021 3:19 am
Affiliation: University of Chicago

Re: Epw BZ related error

Post by azeeshan »

Hi Samuel,

When I use open_grid.x with a coarse automatic grid, I also get the same error since the k points are between -0.5 and 0.5. Is there a workaround to run these calculations if I want to avoid an nscf calculation (e.g. in case of hybrids).

Best,
Zeeshan

hpaudya1
Posts: 190
Joined: Tue Mar 21, 2017 7:11 pm
Affiliation:

Re: Epw BZ related error

Post by hpaudya1 »

Hi Zeeshan,

You can generate the homogeneous coarse grid for the nscf calculations using a script 'kmesh.pl' from wannier90 community, please check inside wannier90-3.1.0/utility or https://github.com/wannier-developers/w ... y/kmesh.pl

For example; if you want to use 8x8x8 mesh; use wannier90-3.1.0/utility/kmesh.pl 8 8 8 >>nscf.in

I hope it helps,

Happy EPWing,
Hari

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