A NEW APPROACH FOR PEROVSKITES IN LARGE DIMENSIONS

Using the Hubbard Hamiltonian for transition metal-3d and oxygen-2p st ates with perovskite geometry, we propose a new scaling procedure for a nontrivial extension of these systems to large spatial dimensions D. The scaling procedure is based on a selective treatment of different hopping processes for large D and cannot be generated by a unique scal ing of the hopping element. The model is solved in the limit D --> inf inity by the iterated perturbation theory and using an extended non-cr ossing approximation. We discuss the evolution of quasiparticles at th e Fermi-level upon doping, leading to interesting insight into the dyn amical character of the charge carriers near the metal insulator insta bility of transition metal oxide systems, three-dimensional perovskite s and other strongly correlated transition metal oxides.