T(2G) VERSUS ALL 3D LOCALIZATION IN LAMO(3) PEROVSKITES (M=TI-CU) - FIRST-PRINCIPLES STUDY

Using the LDA+U method (where LDA is local-density approximation) we s how that a separate treatment of t(2g) and e(g) electrons on transitio n-metal sites as localized and itinerant, respectively, gives an appro priate description for the band structure of LaMO(3) perovskites (M=Ti -Cu) and systematically improves results of the local-spin-density app roximation (LSDA) for the ground-state and single-electron excited-sta te properties. The analysis is based on comparison with experimental m agnetic, optical, and photoemission data. Parameters of the effective Coulomb interaction estimated for t(2g) electrons and a role of e(g) s creening are discussed. The present approach accounts well for the ins ulating natures of LaTiO3, LaVO3, and LaCoO3, for which the LSDA predi cts metallic states. Changes of the LSDA band structure for LaMnO3 and LaNiO3 are almost negligible due to the very efficient screening Of o n-site t(2g) interactions by e(g) electrons.