[Pw_forum] phonon dispersion jagged

[Paolo Giannozzi]

On Oct 28, 2008, at 12:46 , Ante Bilic wrote:

> The calculated dispersion curves were in very good agreement
> with those in the literature, except they look shockingly ugly! For
> some reason they are not smooth, but rather jagged.

are you by any chance running a version later than July 1st (v.4.0.1
and later)? I am afraid that a change I recently made:
http://www.democritos.it:8888/O-sesame/rlog?f=O-sesame/PH/rigid.f90
in order to fix a possible bug and to speedup calculations obeyed the
"bug sum rule", i.e. one bug fixed, one new bug added (thanks to
Andrea Dal Corso for noticing this). Please change the two
instructions at lines 92 and 124 of file PH/rigid.f90:
    if (geg > 0.0 .and. geg < gmax ) then
into
   if (geg > 0.0 .and. geg/alph/4.0_DP < gmax ) then
recompile q2r.x, re-run the "q2r.x" part, report if this fixes your (and
Serge's) problem

Paolo
---
Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222