Form of the hybridization matrix mixing the localized and itinerant electron states in periodic systems

Abstract

We formulate the theorem which shows that the perturbation V which couples two degenerate subspaces can be reduced to coupling in r pairs of states, r equals to the rank of V. We classify according to the presented theorem the possible forms of f c hybridization. If the degeneracies of one-site 4 f subspace and band subspace are different, the nonmixing states can appear.