[QE-users] NaN in output of alpha2f.x

[Hire,Ajinkya C]

Hello,

I am trying to calculate electron-phonon interaction coefficients using the optimized tetrahedron method in qe7.0.
I tried running the example at PHonon/examples/tetra_example/.

In the output of alpha2f.x, I get NaN for omega_ln and 0 for lambda (see below).

```

     Program ALPHA2F v.7.0 starts on 28Apr2022 at 13:56:55

     This program is part of the open-source Quantum ESPRESSO suite
     for quantum simulation of materials; please cite
         "P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);
...
...
...

     Writing a2F to a file aluminum.a2F.dat

     Compute lambda and omega_ln from a2F to verify it.
              lambda :   0.000000000000000E+000
       omega_ln [Ry] :                      NaN

   Compute lambda and omega_ln directly from omega_q and lambda_q

             lambda :   0.334000000000000
     omega_ln [Ryd] :   2.408181004917099E-003
     omega_ln [THz] :    7.92253491785528
       omega_ln [K] :    380.221708280190

   For plotting T_c from the McMillan formula, please type
     $ gnuplot aluminum.McMillan.gp

     ALPHA2F      :      0.20s CPU      0.32s WALL


   This run was terminated on:  13:56:55  28Apr2022

=------------------------------------------------------------------------------=
   JOB DONE.
=------------------------------------------------------------------------------=
```

The frequency column of 'a2f.dat' file looks good but the a2f column just has zeros in it.

I am not sure what is wrong.

I didn't see any warning in the output of self-consistent and phonon calculation.

I used the intel compiler (2019.1.144 version) and openmpi(4.0.3) to compile qe-7.0.




Regards,

Ajinkya Hire
Graduate Student
University of Florida
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