[Pw_forum] Different optical mode frequency at the same q-vector

Lorenzo Paulatto lorenzo.paulatto at impmc.upmc.fr
Mon Oct 15 12:32:05 CEST 2012

On 15 October 2012 07:24, Kyeong-hyun Park <kpark39 at illinois.edu> wrote:

> Dear Dr. Lorenzo Paulatto and other users
> First of all, thank you for your advice.

in order to properly remove the anisotropy   you must also comment out the
           CALL nonanal (nat, nat_blk, itau_blk, epsil, qhat, zeu, omega,
which adds some non-analitical long range term even if lo_to is set to

I also notice that your matdyn complained for a large difference between
the old and new force constants when interpolation, which may signal that
your phonon calculation is non very converged (especially w.r.t the number
of plane waves), or not very stable, or that you are using less symmetry
that you should.

Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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