Ab Initio Study of the On-Site Potential for Divalent Impurities in Dilute Sr1−x A x TiO3 Solid Solutions

Abstract

The off-center impurity model for divalent impurities in SrTiO3 (Mn, Mg, Ca, Cd, Pb, Zn substituted for Sr) is checked. The results of ab initio Hartree-Fock and density functional theory (DFT) B3LYP cluster calculations of the local adiabatic potential for impurity atoms are presented. The results show that all impurity atoms, except Zn and Mg, move in single-well potentials, whereas Zn and Mg in Sr1−x A xTiO3 are found to occupy off-center positions, as does the Li in K1−xLixTaO3, and move in the six-well local potential. It is found that Mn2+ion in a high spin state moves in a flat potential well. The strong effect of electron correlations on the local potentials for Zn and Mg is revealed.