The ABINIT Users Mailing List ( CLOSED )

[DORADO Boris Thésard <boris.dorado@cea.fr>]

Dear Abinit users,

 

I’m currently trying to perform some calculations of phonon frequencies in AlAs, as is done in the first tutorial of the Abinit website.

 

I changed, however, some parameters in order to have a better accuracy of phonon frequencies and to assess the variation of the frequencies with respect to the cutoff and the kpt sampling. I therefore set the cutoff to 400 eV (about 15 Ha, 3 Ha in the tutorial) and the kpt grid to 25x25x25, but the calculation of the phonon perturbation displays this warning along with the phonon frequencies:

 

chkph3 : WARNING -

  The dynamical matrix was incomplete : phonon frequencies may be wrong ...

 

Could someone please tell me why the dynamical matrix would be incomplete? Does it have anything to do with my changed calculation parameters? Because I kept the same input file as in the tutorial except I changed the cutoff and the kpt sampling. I also checked the output file of the tutorial and this warning of course does not appear.

 

In addition, my phonon frequencies are indeed wrong (308 cm-1 and 337 cm-1, instead of something like 359 cm-1 and 390 cm-1).

 

Thank you for your answers.

 

Regards

 

Boris Dorado