Intermediate-valence effects on the phase diagram of NiS2_Xsex.

Abstract

Using a modified Falicov-Kimball model and inlroducing intermedíate valence effects, we reproduce the phase diagram ( T —x) of NiS2_ xS e x . This allows us to develop a simple picture of the physical properties of these compounds based on the concepts proposed to explain the anomalies found in some rare-earth compounds.