[Pw_forum] Wrong degeneracy

[Stefano de Gironcoli]

Shihn Lun wrote:

>Hello Baroni,
>
>I want to check my phonon calculation with
>PRL.v77.p1151.(http://prola.aps.org/abstract/PRL/v77/i6/p1151_1)
>
>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