[Pw_forum] Fourier interpolation

[Stefano Baroni]

the kpoint grid you are using may be too coarse
dynamical matrices in metals are indeed smooth functions of k, unless you have Kohn anomalies
SB

On Jul 28, 2010, at 5:33 PM, HaoPan wrote:

> Hi, everyone,
> 
> On each q point I got, the phone frequencies are positive. But after the Fourier interpolation process, There
> exist negative frequencies. I check the some special q points using ph.x, there are no negative frequencies. I
> know the dynamical matrices for metal are not smooth function of q, but how do I fix it to get the right
> dispersion curves? Thanks a lot.
> 
> Sincerely,
> Pan Hao
> Tulane University _______________________________________________
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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