In order to understand how the electronic structures of grain boundaries were related to their structures, 2 structural models for the Σ = 5 boundary were based on first-principles pseudopotential total-energy calculations. The electronic structure of the bulk crystal, and relaxed grain boundary models, were then studied by using the orthogonized linear combination of atomic orbitals method. Results were presented for the ground-state structural properties and band structure of the bulk material, the total density of states, the atomic and orbital-resolved partial density of states, effective charges, bond order, charge-density distribution and near-edge structure of electron energy-loss spectroscopy. It was shown that the grain boundary structures had smaller values of fundamental band-gaps, effective charges and bond orders; as compared with bulk material. There were no boundary-induced electronic states within, or at the edge of, the fundamental band-gap. The 100-atom grain boundary model, with buckled Sr columns in the grain boundary core, was found to be a more likely model. It was shown that the electron-charge distribution across the grain boundary was almost balanced.

Electronic Structure of a Grain-Boundary Model in SrTiO3. S.D.Mo, W.Y.Ching, M.F.Chisholm, G.Duscher: Physical Review B, 1999, 60[4], 2416-24