[Wien] Interesting effect of RLO's with Spin Orbit

[David Tompsett]

Dear All,

I have been performing calculations with GGA+U with spin-orbit on an Fe and
oxygen based material. I have noticed an unusual effect when using RLO's (
the relativistic local orbitals) for the oxygen p-states. I applied the +U
orbital potential only to the Fe ion and then applied spin-orbit coupling
inside the Fe and oxide spheres.

Without using RLO's for the oxygen p-orbitals the DOS shows a good band gap
(~3eV). However, when I add RLO's for the oxygen p-states I find that there
are states inside the band gap (significant ~0.1 states/eV/FU). The states
have the d-character of the Fe ions. It appears that the flexibility
introduced by the RLO's on the oxygen are changing the description of the
potential such that the groud state has d-orbital character inside the gap.

Does anyone have experience with such an effect? I am unsure as to whether
the effect is real. The oxygen atoms are light, so I expected the RLO's
would have little effect.

I did sensible things like converge with respect to the emax in case.in1,
k-points, IFFT factor=4.

Many thanks for your help,
David Tompsett.
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