[Pw_forum] About el-ph coupling

[Eyvaz Isaev]

Hi,

--- On Tue, 11/25/08, Dai <jdai3 at mail.ustc.edu.cn> wrote:

> More simply, if I perform a
> phonon calculation using FM and AFM configurations, will
> there be any difference in the phonon spectrum and the
> coupling constant?

from phq_readin:

IF (elph.AND.lsda) CALL errore ('phq_readin', 'El-ph and spin not implemented', 1)

At least, for QE_4.0 and earlier versions.

As concerns an influence of different magnetic ordering (FM and AFM), yes, you can see the difference in the phonon spectrum. Of course, in this case you should use the same structure for both FM and AFM calculations, but introducing AFM ordering you reduce the symmetry. 
 
Bests,
Eyvaz.

-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com