[Pw_forum] My phonon dispersion curves are jagged too

[Nicola Marzari]

Dear Serge,


in the past we encountered a problem in the cubic perovskites,
in which the davidson algorithm would converge the top band
at some k-points to an "excited state". This is, afaik, a problem
with some algorithms (much more so with diis); a simple
solution was to use "atomic+random" as a starting point, and maybe
use "cg" as the minimization strategy in the scf calculation,
with a very tight tolerance.

Try that, maybe without redoing the phonons, just to see if the
calculations converge to the same ground state, or to a lower one.

					nicola




Serge Nakhmanson wrote:
> Dear All,
> 
> I am learning how to compute phonon dispersion curves across the BZ and
> right now I am trying to reproduce the results of a simple calculation
> for cubic perovskites that Philippe, Karin and company have done a long
> time ago [PRB 60, 836 (1999)].
> 
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Prof Nicola Marzari   Department of Materials Science and Engineering
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