Yes, Andrei is absolutely right: Zn is not a good example of using SZ
for semicore - it's d-states overlap with s-band, and therefore should
be more considered as "valence". SZ should be OK for such elements as As
or Ga, where these states are located deeper in energy, and therefore
are more localized. But in any case, as Andrei pointed out, everything
depends on what you would like to obtain, and you should always check
your particular desired quantity for convergence. (I saw results of big
supercell calculations, where people freeze Zn 3d, putting it in
pseudopotential. However, I would not recomment that ...)
Thanks for your comment, Andrei!
Vladimir.
Andrei Postnikov wrote:
On Fri, 26 Jan 2007, Vladimir Timochevski wrote:
| Usually semicore states are quite localized, and from my experience a SZ-type
| of orbitals is sufficient for them. So, in case of Zn (3d10 semicore states)
| put something like
| %block PAO.Basis
| Zn 2
| n=4 0 2 P
| 0.0 0.0
| 1.0 1.0
| n=3 2 1
| 0.0
| 1.0
| %endblock PAO.Basis
| This will give you 2 4s-orbitals, 3 4p-orbitals, and 5 3d-orbitals. Cutoff
| radii will be generated automatically.
Dear Vladimir:
This is indeed a quite risky advise... of course the final decision depends on
what you are doing and level of accuracy you need.
You'll probably get the position of Zn3d band right with SZ,
but lattice parameter, elastic propeties, and phonons could be quite off.
3d of Zn is hardly a good semicore,
it is really too close and contribute substantially to bondings.
Best regards,
Andrei
