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 > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- Michael J. Mehl Naval Research Laboratory Washington DC
