[Pw_forum] Abinitio calculation for Iridium

Paolo Giannozzi p.giannozzi at gmail.com
Tue Jun 9 18:28:40 CEST 2015

In metals, the convergence of phonons with respect to the k-point grid can
be quite hard.
For some obscure reasons, if the following conditions are met:
- phonon wave-vector q not commensurate with k-point grid
- semicore electrons in valence
convergence is especially hard.


On Tue, Jun 9, 2015 at 9:09 AM, Umesh Roy <umesh24crp at gmail.com> wrote:

> Dear All,
>            I have a problem of determining the phonon calculation for
> iridium at high symmetry points. I calculated the phonons at different high
> symmetry points for different set of k grid (used in the first part of scf
> calculation). I get different phonon frequencies for each set of k grid at
> any particular  phonon wave vector q. The variation in phonon frequencies
> is not negligible in fact 40-50%. How is it possible? Here in the following
> I attached the input files for pwscf and phonon calculation. Please help.
>           Thank you in advance.
> *---------------------------------------------------------------------Umesh
> Chandra RoyResearch Scholar, School of Physical SciencesJawaharlal Nehru
> University, New Delhi-110067,*
> *India.*
> *Email:umesh24crp at gmail.com <Email%3Aumesh24crp at gmail.com>*
> *Mobile:+919868022722 <%2B919868022722>*
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Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
hone +39-0432-558216, fax +39-0432-558222
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