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hello,

I have calculated the Electron-phonon interaction, but I constantly get an error. Firstly, I calculated for Al atom in the Specialized lessons-Electron-phonon interaction. I didn't get any error. Then, I calculated for MgO(because, MgO has same space group with Al) by using same procedures;

1) I calculated for ground state MgO
for ngkpt 2 2 2
kpt 0.00000000E+00 0.00000000E+00 0.00000000E+00
5.00000000E-01 0.00000000E+00 0.00000000E+00
5.00000000E-01 5.00000000E-01 0.00000000E+00

2) I calculated for the telphon_1.in file by using,
qpt2 0.00000000E+00 0.00000000E+00 0.00000000E+00
qpt3 5.00000000E-01 0.00000000E+00 0.00000000E+00
qpt4 5.00000000E-01 5.00000000E-01 0.00000000E+00

ngkpt 2 2 2 and Common data for MgO
3) mrgddb < telphon_2.in and mrggkk < telphon_3.in, no problem

4) finally, I have started the telphon_4.in file by using anaddb but there is an error as follows;
.
.
Calculation of the interatomic forces

-begin at tcpu 0.091 and twall 0.091 sec
mkifc9 : enter chkrp9
mkifc9 : exit chkrp9
mkifc9 : enter smpbz
Homogeneous q point set in the B.Z.
Simple Lattice Grid
Grid q points : 8
1) 0.00000000E+00 0.00000000E+00 0.00000000E+00
2) 5.00000000E-01 0.00000000E+00 0.00000000E+00
3) 0.00000000E+00 5.00000000E-01 0.00000000E+00
4) 5.00000000E-01 5.00000000E-01 0.00000000E+00
5) 0.00000000E+00 0.00000000E+00 5.00000000E-01
6) 5.00000000E-01 0.00000000E+00 5.00000000E-01
7) 0.00000000E+00 5.00000000E-01 5.00000000E-01
8) 5.00000000E-01 5.00000000E-01 5.00000000E-01
mkifc9 : exit smpbz
mkifc9 : enter symdm9
symdm9 : ERROR -
Informations are missing in the DDB.
In blok 3 the following element is missing :
idir1,ipert1,idir2,ipert2= 1 2 1 2
Action : add the required information in the DDB,
or modify your input file.

leave_new : decision taken to exit ...

I could not find a solution for this eror although I reviewed in and out file, similar problems in the forum. Can someone help me understand what the problem is ?

best regards

You have not done all the needed perturbations at the given q-points: anaddb is complaining about this, and the message is relatively clear... Same as for the rf tutorials for AlAs:

you need rfatpol 1 2 rfdir 1 1 1
and, for elphon:
prepgkk 1 # force all perturbations explicitly
prtgkk 1 # print out g_k,k' matrices

NOTE: for MgO the default el-ph calculation will give 0. The quantities are integrated over the Fermi Surface - for insulators you get nothing. You can shift the Fermi level using elph_fermie in anaddb.

matthieu

Thank you very much for your answer.
you're right, the error is related to rfatpol parameter that I have used it to 1 1. When I have used it as 1 2, calculation works without any problems.

I would like to ask one more question about this tutorial. "Electron-phonon interaction->telphon_3.in" input file;
0 9 9 # number of 1WF files, of GKK files, and of perturbations in the GKK files for Al
I used for MgO that;
0 48 48 (ngkpt 4 4 4)

I haven't understand fully number of perturbations in the GKK files. Is it always equal to the number of GKK files?

In principle you could be merging GKK files with several perturbations in a given file. These are read through and appended correctly, but for the header of the final merged file you need to know how many perturbations it will have in the end.
Usually, #(GKK files) = #(perturbations)

matthieu