METALLIC NON-FERMI-LIQUID PHASES OF AN EXTENDED HUBBARD-MODEL IN INFINITE DIMENSIONS

We study an extended Hubbard model in the limit of infinite dimensions and its zero-dimensional counterpart, a generalized asymmetric Anders on model. In the impurity model we find three kinds of mixed valence s tates: (a) the usual strong-coupling state in which a resonance forms at the Fermi level; (b) a weak-coupling state in which neither the imp urity spin nor the impurity charge degrees of freedom are quenched; an d (c) an intermediate-coupling state where the spin but not the charge degree of freedom is quenched. The corresponding phases of the extend ed Hubbard model in infinite dimensions are (a) a Fermi liquid; (b) a non-Fermi-liquid state with incoherent charge and spin excitations; an d (c) a non-Fermi-liquid state with incoherent charge but coherent spi n excitations. The non-Fermi-liquid phases are incoherent metallic sta tes with vanishing quasiparticle residue, self-similar local correlati on functions, and asymptotically decoupled charge and spin excitations . The non-Fermi-liquid phases occur for a wide range of parameters.