[Pw_forum] Negative frequence at Gamma point and other kpoints.

[方子明]

Dear Experts,
Recently, I have done some phonon calculations about NaFeAs, I noted that some negative frequencies appears at Gamma point. 
I have also done calculationphonon dispersion for LiFeAs, and again I found some negative frequencies. 
My input files are attached with mail.
Thanking in anticipation for answering my question.
Regards,
Ziming Fang.








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