[CPMD-list] a "quality" criterion in plane-wave calculations

[Ari.P.Seitsonen at iki.fi]

Dear Jaroslaw,

> what is your opinion on the choice of quality crierion in the plane wave
> computations? The cutoff energy comes to mind first, but I have seen other
> proposals in the literature. People have tried to keep constant the number
> of plane waves per electronic state or the "density", i.e. number of plane
> waves per unit volume. Do these parameters help when comparing e.g.
> systems with different numbers of electrons, or can they help with
> variable cell problems? I would be grateful to read your opinions.

The constant number of plane waves is only used/useful when the size
and/or shape of the cell is changed, like you write. This doesn't make
a difference when the number of electrons is altered.

  Now, the discussion on the constant number versus constant cutoff
has been discussed a couple of times in the literature, and there are
for example the papers by Payne et al and Gonze et al - mentioned
earlier on this mailing list - which are related to the topic.

    Greetings,

       apsi

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