[Q-e-developers] phonon dispersion with experimental structure

[Lorenzo Paulatto]

On 04/15/2013 09:06 AM, ding wrote:
> Hi everyone,
>  Does one have to relax the structure before doing phonon 
> calculations?  If I calculate the phonon dispersion of a material with 
> the experimental structure at different pressures, Can I get get the 
> phonon dispersion without negtive frequencies ?
>

Dear Ding,
it is normally possible only for highly symmetric materials.

Please use the pw_forum mailing list for this kind of help requests 
<http://www.qe-forge.org/mailman/listinfo/pw_forum>; the q-e-developers 
list is reserved to discussion about the *development* of the QE codes.

best regards

-- 
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 5