[Pw_forum] dynamical matrix

[Eyvaz Isaev]

Hi again,

In this case I suggest you can try increase k-mesh and
cutoff energy. 
Actually, in some cases it is difficult to get good
phonons and it is due to peculiarities of the band
structure, say, flat portions. I had this problem for
R-point in Ni3Al (see Sol.St.Comm. 129 (2004)
809–814).

Bests,
Eyvaz.

--- Alberto Milani <alberto.milani at chem.polimi.it>
wrote:

> Dear Eyvaz,
> I have already tried changing thr2_ph from 1d-10 to
> 1d-12 and even more.
> Unfortunately, my longitudinal acoustic frequencies
> are still not good enough 
> (the geometry of my system has been carefully
> optimized and any kind of 
> instabilities have been removed). 
> Have you any other suggestion?
> Thank you very much.
> A.M.
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