[Pw_forum] phonon dos of Fe

[Michael Mehl]

 From which I infer that you are not doing a spin-polarized calculation 
for iron -- the lowest energy structure for non-polarized iron is hcp, 
with fcc right above it, and bcc significantly above that.  For 
non-polarized bcc Fe, C11 - C12 < 0, which implies imaginary phonon 
frequencies at least near Gamma.

Turn on spin polarization and try it again.

Fang, Yuan wrote:

> Hey;
>    Nowadays,I am calculating the phonon DOS of some elements.But I got some really strange result of Fe-bcc structure.I got some states with minus frequency. Attached is mu input file and output frequency file. Can someone help me find where the problem is.Thank you very much.
>                                Y Fang
> 
> 
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-- 
Michael J. Mehl
Naval Research Laboratory
Washington DC