ABINIT Discussion Forums

Dear all
I am trying to calculate electron phonon coupling constant for Al, like in the tutorial.
I got it right for unit cell 0.44 but when I tried super cell 2*2*2 the constant is 0.205
I think the issue is in qpath in anaddb input file
for the unit cell the qpath was
nqpath 7
qpath
0.0 0.0 0.0
1/2 1/2 0.0
1 1 1
1/2 1/2 1/2
1/2 1/2 0.0
1/2 3/4 1/4
1/2 1/2 1/2

should I change the qpath and how to get the right path, I have no clue
please help
Thanks

Hello,

interesting, but the qpath has nothing to do with it - it is just for representation of band structures and lambda(q). The total lambda should be the same. Have you checked
1) that the phonons are the same (folded) as in the unit cell
2) that your convergence is as good as in the primitive cell (what is the omega_log?)
3) you have no instabilities etc...
4) how do the DOS and A2F functions compare?

If all this is ok, it could be that there is a normalization issue in calculating the lambda, though I doubt it. If your k grid is not fine enough you will not get a good enough integration and lambda will not be converged. In particular, even though you have a supercell, it may not be possible to halve the k-grid and still get a good integration of the epc over the Fermi Surface.

ciao

Dear Matthieu Verstraete

Thanks for your reply, your notes were very useful. thank you very much.
can you please give me more details about the fist note.
I am still beginner in the field.


Thanks

Dear Abinit users,
I got a problem, while calculating the ElPhonTransport properties of Mono layer of MOS2 (Molybdenum DI sulphide).
--- !ERROR
src_file: read_gkk.F90
src_line: 269
mpi_rank: 0
message: |
found too many qpoints in GKK file wrt anaddb input
nqpt_anaddb nqpt_gkk = 6 7
...
here, i upload my input files.
any one help Me to solve this problem
thank you in advabce