[Pw_forum] calculating lambda for a phonon band structure with imaginary frequencies

[Guoying Gao]

On Dec 9, 2007 9:06 PM, Stefano Baroni <baroni at sissa.it> wrote:
> Imaginary frequencies are usually a sign of a mechanical instability, as
> discussed many times in this forum as well as in many condensed-matter
> textbooks. I think the answer is yours: if you want to calculate the
> electron-phonon interaction of an instable (possibly metastable) phase of a
> material, please do. If instead instability is soemething that troubles you,
> then you better settle your troubles first. Cheers - SB
Hi Stefano,
     Thanks for your reply.
     I know the imaginary frequencies signifying a mechanical
instability, but I want to know whether we can calculate it or not and
is it meanful to do this? We just want to estimate the values of Tc.
Guoying