Electronic Structure and Excited-state Properties of Perovskite-like Oxides

Abstract

The role of structural distortion, magnetic ordering, and Coulomb-correlation effect on the electronic structure of perovskite-like oxides is analyzed. The density-functional theory (DFT) is originally devised to describe the ground-state properties of materials. However, during recent years it has been seen that the DFT can also be used to study excited state properties succesfully. We have recently calculated the electronic structure and linear optical properties for the series LaXO 3 (X=Sc–Cu) and found that the gradient-corrected DFT describes correctly the insulating behavior of the ionic insulator LaScO 3 and the charge-transfer insulators LaCrO 3, LaFeO 3, and LaMnO 3 although the band gaps are systematically underestimated. For example, the good agreement between experimental and theoretical reflectivity spectra for LaCrO 3 clearly demonstrates that accurate full-potential DFT calculations not only describe the occupied and unoccupied states of the bands well, but also reproduce their characters. We have also calculated XPS, XANES, and magneto-optical spectra for perovskite-like oxides. For Mott–Hubbard insulators such as LaTiO 3 and LaVO 3 the DFT failed to predict insulating behavior and here the LDA+ U method is applied to describe the electronic structure correctly.