Diagrammatic theory for twofold degenerate Anderson impurity model

Abstract

We study the influence of the intra-atomic Coulomb interactions of the two electrons with opposite spins situated on the same or different orbitals and intra-atomic exchange is analyzed. We discuss the properties of the Slater-Kanamori model [1-3] of d-impurity electrons. After finding the eigenfunctions and eigenvalues of all 16 local states, we determine the local one-particle propagator. We have formulated the diagram theory for the two orbital degenerate Anderson impurity model by generalizing the perturbating theory formulated for strongly correlated non degenerated electronic systems. Perturbation theory was formulated around atomic limit of impurity localized electrons. We determined the correlation functions as a sum of strongly connected irreducible diagrams and have formulated Dyson type equation for the full propagators of conduction and impurity electrons. Special diagrammatic approximation was discussed and summation of diagram has been considered.