[Pw_forum] Wrong degeneracy

Stefano de Gironcoli degironc at sissa.it
Thu Mar 3 09:15:45 CET 2005

Shihn Lun wrote:

>Hello Baroni,
>I want to check my phonon calculation with
>Thanks for your reply.
>Shihn Lun
If you read carefully the figure caption of PRL 77, 1151 (1996) it is 
said that
"directions of propagation and polarizations are espressed in terms of the
reciprocal lattice vectors"

The N point in a BCC Bravais lattice --- corresponding to (0.5,0.0, 0.0) 
in that figure ---
IS NOT the (0.0 0.0 0.5)  point (in cartesian coordinates in unit of 
2pi/alat) you are
computing with ph.x !
It would rather be (0.5,0.5,0.0)

best regards,

stefano de Gironcoli

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