[Pw_forum] Displacements corresponding to -ve Phonon modes
Stefano Baroni
baroni at sissa.it
Tue Oct 5 07:45:32 CEST 2010
On Oct 4, 2010, at 3:07 PM, Bipul Rakshit wrote:
> Dear PWSCF users,
>
> I am doing Phonon of KO2 compound. I find some -ve phonon modes at gamma point. (After applying ASR also)
> Following is the dynamical matrix formed by the phonon programme during the run.
> I just want to study the displacement corresponding to -ve modes. So Is it enough to plot the eigen vectors given below corresponding to each mode.
> Strange things what I feel in these eigen vectors are the 'K' is also moving almost with the same magnitude as 'O'
Not so strange for zone-center acoustic modes (their frequency is zero exactly because they correspond to a rigid translation)
> and there is no imaginary part of eigen vectors though the frequencies are -ve.
why should there be any?
what do you mean by "-ve"?
SB
---
Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Trieste
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