[Pw_forum] What happens at REALLY large ectuwfc?

[Paolo Giannozzi]

Brad Malone wrote:

> The results I posted are from espresso-4.0.5, although 
> I originally saw this problem with espresso-4.1.1 in a 
> different system (AlAs on a 2x2x2 shifted grid).

start with 'random' or 'atomic+random' initial wavefunctions
(startingwfc='...'). I didn't find anything wrong with very
high cutoffs. Occasionally you can end up in the wrong ground
state, though, especially in highly symmetric cases like the
Si example you sent.

"Ghost states" are another story. It may happen that a
(nonlocal, separable) pseudopotential has a localized
spurious state that doesn't show up (i.e. it is not
occupied) at low cutoff, but it is occupied at higher
cutoff. None of the PP on the QE web site should have
such states, though.

If you have evidence of further problems, please provide
a test case so that it can be reproduced. In any case,
thank you for finding a bug in the cvs version!

P.
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Paolo Giannozzi, Democritos and University of Udine, Italy