Relevance of inter-site Coulomb repulsion on high-Tc superconductivity within t−J−V model

The relevance of inter-site Coulomb repulsion (V) in the hole-doped cuprates is explored within t−J−V model. An exact diagonalization (ED) technique is employed to investigate some ground state and thermodynamic properties of the model for various hole-doping. Results show that electron-electron (e−e) correlation is maximum between the next-nearest-neighbor (NNN) sites which decreases sharply at distances longer than √2 times the lattice spacing. Unlike hole-concentration, Coulomb repulsion reduces effective hopping amplitude. Our results suggest that in this hole-doped system, inter-site Coulomb repulsion favors d-wave pairing. Specific heat curves show characteristic single broad peaks where the peak-height decreases with doping concentration. From specific heat and entropy curves, one can expect a superconducting state at =0.25.