[Wien] lcore stops

[Fred Nastos]

On November 8, 2004 04:39 pm, Peter Blaha wrote:
> > > You should never run a case where identical atoms (Si) have different
> > > radii !
> >
> > I don't understand why?  The Si atoms are inequivalent.  I only
> > chose a smaller one for the Si atom near the hydrogen-terminated
> > surface.  Is it because of some basis-function mismatching problem
> > at the muffin-tin surface between the two Si atoms?
>
> This means according to the variational principle that you choose a poorer
> basis set for the atom with the smaller sphere. It will lead to higher
> eigenvalues for this atom, and thus may introduce some artificial charge
> transfer,......

I think I understand what you are saying.  The artificial charge transfer is
an interesting point I never thought of.

But still, if I make the spheres smaller for all the Si atoms, then I have
a poorer basis set for all Si atoms and thus still higher eigenvalues,
right?  Or is it that the artificial charge transfer is dangerous and
should be avoided at all costs?  (I could imagine it leading to
different local potentials, maybe breaking symmetry or something
else equally bad.)

> This is also the reason for the RMT rules (see faq page on the web).

Maybe in the section called "How to select RMT radii?" found at
	http://www.wien2k.at/reg_user/faq/rmt.html
you could add Rule 8, that RMT radii should be the same for the same
species.

Thank you.

> These rules guarantee that you get the most "ballenced" basisset.
>
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW:
> http://info.tuwien.ac.at/theochem/
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