Valence instability in an extended periodic Anderson model

Abstract The valence instability in an extended periodic Anderson model is studied with the dynamical mean field theory combined with exact diagonalization. It is found that at fixed total electron number ( n tot = 1.75 ) , the f -electron number is rapidly decreased against the f -electron level in the presence of the repulsive interaction U cf between a conduction electron and an f electron. This implies the enhancement of valence fluctuations due to U cf . In addition, a first-order valence transition is likely to occur, provided the c – f mixing is small and U cf is large enough to be comparable to the bandwidth of conduction electrons.