S. K. S.
sks.jnc at gmail.com
Wed May 11 14:35:20 CEST 2011
Thanks a lot for your quick reply.
Yes, both set of the frequencies are
obtained after imposing ASR. All of
frequencies are not negative. Two of
the modes among total 5 modes
(triply generate) are negative, which are
not very unusual in a BaTiO3-type cubic
Saha S. K.
On 5/11/11, Stefano de Gironcoli <degironc at sissa.it> wrote:
> are you imposing acoustic sum rule ? this change slightly the frequencies .
> isn't strange that your frequencies are all negative (imaginary) ?
> is your system stable ?
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