[Pw_forum] a question about phonon dos
giannozz at nest.sns.it
Wed Aug 9 10:42:47 CEST 2006
On Thursday 03 August 2006 17:41, Peter Winey wrote:
> In the description part (head) of the program, I noticed the following:
> "dos if .true. calculate phonon dos using tetrahedra and a uniform
> q-point grid. NB: may not work properly in noncubic materials."
> Could someone kindly explain to me what "using tetrahedra" means?
it means "using the tetrahedron method to perform sums over
the Brillouin Zone". See for instance:
P.E. Bloechl et al, PRB49, 16223 (1994)
> if the program does not work properly for noncubic materials,
> how to get the proper phonon dos?
it is not that it doesn't work at all, but there will be a small
error in the contribution of the region around q=0. It is not
clear to me how to take into account the dependence of LO
phonons at q=0 upon the direction of q=>0
Paolo Giannozzi Phone: +39/050-509876
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