[Wien] eigen-spin treatment in core states calculation

[Peter Blaha]

You are absolutely correct, we do an approximation here.
However, the spin-mixing for core states is negligible small. This was tested in a paper by
Guo,.. Blaha  on bcc Fe.



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In the calculation of core states, Wien2k treats the spin-up electron and spin-down electron respectively

from their full relativistic Dirac equations. However, in such calculations the spin(S) is not good quantum number

of the system, but the total angular momentum(J=l+S). Actually, in the /SRC_lcore/insld.f the spherical potential file

"case.vspup" is read for solution the "spin-up" Dirac equation and "case.vspdn" for solution of "spin-dn" Driac equation.



Anyone can give me some tips to understand such treatment of independent "spin-up" and "spin-down" electrons

with the framework of Dirac equation? In full relativistc situation, the spin-up and spin-down states are always mixed together

such that the eigen-spin states actually do not exist.





Thanks so much.

Wenmei Ming

                                       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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