[Pw_forum] non degenerate phonon frequency for cubic crystal along 1 0 0

[Paolo Giannozzi]

On May 12, 2011, at 17:43 , mayank gupta wrote:

> The phonon frequency for cubic crystal should have degenerate
> along [1 0 0] for TA modes, But i got different frequency. I have
> calculate  the same with larger value of ecut_rho as well as with
> higher FFT mesh and still they are non degenerate.

symmetry doesn't change with the cutoff. You may want to try
a tighter convergence criterion (tr2_ph)

P.
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Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222