[Pw_forum] Negative frequencies at really low threshold convergence

[Paolo Giannozzi]

On Aug 23, 2012, at 20:46 , Elie M wrote:

>  I still get that the three first values of the frequencies are  
> negative.
> Does this confirm the instability of the system?

likely, but you should first of all verify the effect of applying the
Acoustic Sum Rule.

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