Extended periodic Anderson model close to a valence transition: A projector-based renormalization approach

Abstract

The one-dimensional periodic Anderson model with an additional Coulomb repulsion ${U}_{fc}$ between localized $f$ and conduction electrons has been investigated using the projector-based renormalization method. Due to the presence of ${U}_{fc}$ and the hybridization $V$ between localized and conduction electrons, various gaps are found in the quasiparticle dispersion ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\epsilon}}}_{k}$. The number of gaps depends on the density of the localized electrons. Moreover, a valence transition from an integer to a mixed $f$ valence is found as a function of the bare $f$ level energy ${\overline{\ensuremath{\epsilon}}}_{f}$. Its dependence on various model parameters is investigated for fixed total electron density. In particular, the transition is sharpened either by increasing ${U}_{fc}$ or by decreasing the hybridization or the temperature.