ELECTRONIC-STRUCTURE AND LATTICE-RELAXATION RELATED TO FE IN MGO

The electronic structure of Fe impurity in MgO was calculated by the linear muffin-tin orbital-full-potential method within the conventional local-density approximation (LDA) and making use of the LDA + U formalism. The importance of introducing different potentials, depending on the screened Coulomb integral U, is emphasized for obtaining a physically reasonable ground state of the Fe2+ ion configuration. The symmetry lowering of the ion electrostatic field leads to the observed Jahn-Teller effect; related ligand relaxation confined to tetragonal symmetry has been optimized based on the full-potential total-energy results. The electronic structure of the Fe3+ ion is also calculated and compared with that of Fe2+.