Impact of NNN Coulomb interaction on the Properties of Mixed-valence Compounds

The influence of Next Nearest Neighbour (NNN) Coulomb-interation on mixed-valence systems has been investigated. We have considered Falicov-Kimball model ex­tended by the NNN Coulomb interaction. Exact diagonal­ization technique has been used to study the zero and finite temperature properties of the mixed valence compounds. It has been revealed that NNN Coulomb interactions (i) relocates the f-level energy and effects the valence transition,(ii) escalates disorder in the system, (iii) both single peak and double peak structures become prominent in specific heat curves, (iv) raises the growth of antiferromagnetic correlations