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