Ab initio study of bulk and surface iron defects in SrTiO₃

Hybrid HF-DFT LCAO approach with B3PW exchange-correlation functional was employed for the calculations of bulk and surface Fe⁴⁺ impurities in SrTiO₃ for various iron contents. Structural and energetic changes in the host material induced by defect incorporation were particularly addressed. The calculated Jahn-Teller distortion around the iron defects in the bulk were compared with recent experimental EXAFS results. It was found that the iron defects have propensity to segregate to the (001) surface and substantially reduce the basic properties of SrO-terminated surface.