Charge Ordering and Phase Separations in the Spinless Fermion Model with Repulsive Intersite Interaction

Abstract

We study a simple effective model for description of charge orderings in narrow band materials, i.e. the spinless fermion model with repulsive intersite interaction W . The analysis is concentrated on the problem of phase separations and the effects of next-nearest neighbor hopping t2 on the charge ordered states in this system. The cases of d-dimensional (d ≥ 2) hypercubic lattices are considered for arbitrary particle concentration (0 < n < 1). Within the broken symmetry Hartree–Fock approximation the phase diagrams as a function of W and n are evaluated for representative cases. The results for t2 6= 0 are compared with those found for the case with nearest neighbor hopping only.