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["Erik Ylvisaker" <eylvisaker@physics.ucdavis.edu>]

I am doing a calculation of the Gamma point phonons in LiNbO2, which seems to complete ok.  After including electric field calculations and using anaddb to examine non-analyticities in c direction to find LO modes I see some strange behavior.. namely that one frequency actually decreases (85.5 meV -> 70.0 meV), and particular eigenmode vanishes and is replaced by another eigenmode.  All three of these modes have A2u symmetry.  Polarization in x-y direction behaves as one would expect.

 

Following PRB55, 10355 (1997), I see that it is reasonable that the eigenvectors might change, but the change in eigenfrequency should be positive, I think.

 

Attached are input files for abinis and anaddb.  The mode which has appeared is in the last one in the last list of eigenvectors: #24, with an energy of 96.3 meV. 

 

~Erik Ylvisaker

 

Attachment: anaddb.outL
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Attachment: anaddb.in
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Attachment: born.in
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