Single-particle properties of the extended Hubbard model in the Composite Operator Method

Strongly correlated electron systems with planar structure, like high--$% T_{c} $ superconductors, are currently under intensive study. In the search for a realistic model to describe the anomalous behaviors of these systems, we have studied the 2D Extended Hubbard model by means of the Composite Operator Method. The local properties, the density of states and the Fermi surface have been calculated as functions of the model parameters. Particular attention has been paid to the role played by the intersite interaction $V$ which drives important changes in the electronic properties of the system