Formation of midgap states due to charge frustration

Abstract

We investigated the effects of charge frustration in the spinless fermion system on a triangular lattice with bond anisotropies under strong intersite Coulomb interactions. Using the exact diagonalization method, we calculated the density of states for various values of bond anisotropies. Results indicate a partial melting of charge ordering by increasing the amount of frustrations (from a square lattice to an isotropic triangular lattice), which leads to the formation of a midgap states. Due to the midgap states, the system seems to be metallic.