Strongly Correlated 5fElectrons: Spectral Functions and Mean-Field Ground States

Abstract

Model spectral functions for 5 f systems are calculated within Cluster Perturbation Theory. The low-energy spectra exhibit dispersive quasiparticle peaks co-existing with an incoherent background. Within the present model the dual character of the 5 f electrons arises from strong intra-atomic correlations. The ground states of extended 5 f systems are analyzed treating the intra-atomic correlations within mean-field theory. The calculations confirm the qualitative results derived by exactly diagonalizing the Hamiltonian for small clusters. A characteristic feature of the spectral functions in systems with strong intra-atomic correlations are high-energy peaks associated with transitions into excited atomic multiplets. First theoretical results for UPd 2 Al 3 are presented. The calculations start from LDA conduction bands accounting for the intra-atomic correlations among the 5 f electrons in terms of an atomic-like selfenergy.