[Wien] lcore change from wien2k_02 to wien2k_03

[Peter Blaha]

> I have seen in the literature some treatments of core tails.  Are these
> not implemented in wien2k?

No, WIEN does not have a proper core tail treatment, but simply cuts those
tails off (and puts them in as a constant charge in the interstitial during
renormalization in mixer.)
We had from beginning on the "local orbitals" for the treatment of
semicore states, with the philosophy that when core tails "overlap" they will
also "interact" and thus should be treated as "bands".
However, I admit that in a case like yours the treatment of
P-2p as semicore is probably an overkill and a simple coretail superposition
would be sufficient. (I usually put Si 2p as semicore in short Si-O bonds,
where Si 2p is around -7.5 Ry; but the heavier P will have these states
even lower)

> For example, we have
> :NEC01: NUCLEAR AND ELECTRONIC CHARGE  304.00000 303.97497   1.00008
>
> This is mostly due to a phosphate group (PO4) which we have treated by
> choosing RMT=(P-O bond)/2.  In a pseudopotential treatment, we would
> choose the equivalent of RMT to be larger for P than for O in order to
> reduce the core "leakage", but my reading of your userguide and other
> sources encouraged me to choose RMT to be equal for P and O.  Was that a
> bad idea?  If we had chosen a larger RMT for P than O, we would probably
> have needed to choose a larger value for RKMAX and/or worry about ghosts?

Yes, with a smaller O-sphere you would have needed a larger RKMax and much
more computational effort.
Leakage is not that large.
Probably I would have made the same choice as you did.

Try testing if the correction gives a "constant" shift in a few cases.

Regards

                                      P.Blaha
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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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