Dear Developers,
I am trying to calculated phonon frequencies at the Gamma point. I understand this can be done using tag IBRION=5 or 6 with the difference that the first one does not include any symmetry considerations.
What I do not understand is that my result with IBRION=6 depends also on the used ISIF tag (even if NSW=0). In particular, for IBRION=6 and ISIF=2 I get similar results (up to numerical noise, I suppose) with IBRION=5, but when using ISIF=4 or ISIF=6 (to get simultaneously also the elastic constants), the obtained frequencies differ. Why?
Thanks,
David
Phonon eigenfrequencies with IBRION=5/6
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dholec
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Phonon eigenfrequencies with IBRION=5/6
Last edited by dholec on Wed Mar 05, 2014 3:29 pm, edited 1 time in total.
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support_vasp
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Re: Phonon eigenfrequencies with IBRION=5/6
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