[Pw_forum] phonon calc. for fcc at X

[e kb]

  Dear Stefano,
  Thank you, I will study the relevant part for pert. potential., do the suggested tests and modifications,
  and send the result back to close the case.
  But a fast point that I wanted to note that is,
  InN turns out to be a metal according to my calculations,
  without several corrections used, like GW or SIC.
  That was the reason of the k-mesh.
  Thank you for your help.
  
Emine Kucukbenli
  
Stefano de Gironcoli <degironc at sissa.it> wrote:
  
If I remember correctly there used to be a term in the phonon 
calculation in which the perturbing potential was written as DeltaV(r) = 
exp(+iqr)*\DeltaVperiodic(r) and \DeltaVperiodic was expanded up to
the charge density cutoff ... this term was therefore slightly different
for two q wavevectors that would otherwise be equivalent. This never
gave any noticeable difference in real calculations and I would be 
surprised if this would be the cause of your results but a way to check
this is to increase the charge density cutoff and see what happens as
in this case the problem should disappear when the potential description
become complete.