internal error, cannot bracket Ef

Running EPW
1

Dear users and developers,

In epw.x calculation, the below problem is occured.
I think that it is because of wrong input in epw.in file.

I used the values
for phonon calculation,
12x12x12 k-mesh & norm-converge PP in scf.in
2x2x2 q-mesh in ph.in

for epw calculation,
12x12x12 k-mesh & norm-converge PP in scf.in
8 k-points in nscf.in
nbndsub =3 for px,py,pz in epw.in (due to localized 3 bands near Fermi level)

Please, could you give me any idea?

==================================================

 Writing epmatq on .epb files


          band disentanglement is used:  nbndsub =    3

 Writing Hamiltonian, Dynamical matrix and EP vertex in Wann rep to file


 Reading Hamiltonian, Dynamical matrix and EP vertex in Wann rep from file

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine efermig (1):
internal error, cannot bracket Ef
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 stopping ...

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine efermig (1):
internal error, cannot bracket Ef
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 stopping ...

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine efermig (1):
internal error, cannot bracket Ef
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 stopping ...

 Finished reading Wann rep data from file

 Using uniform q-mesh:    2   2   2
 Size of q point mesh for interpolation:          8
 Using uniform k-mesh:    2   2   2
 Size of k point mesh for interpolation:         16
 Max number of k points per pool:                4

 Fermi energy coarse grid =   7.312544 eV

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine efermig (1):
internal error, cannot bracket Ef
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 stopping ...
2

Dear Myung-Chul,

You need to make sure that the band structure after Wannierization is correct. I see that you are only using 8 k-points in nscf.in, this may not be enough. You could try 64 k-points instead.

If your Wannierization is correct, a way to go around the error is to set the Fermi energy in the input epw.in This was discussed here:

viewtopic.php?f=6&t=113&p=504&hilit=bracket+Ef#p504

Best,
Roxana

3

Dear Roxana,

Thanks for your reply.
To begin with, I tried to set the fermi energy, and then I was able to have a result.
But I should check either the wannierization is correct or incorrect, because I got the strange band structure.

Thank you,
Myung-Chul