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. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20110421/57ea42a2/attachment.htm>