In this thesis, we develop a dynamical mean field approach to strongly correlated electron systems. Our approach is based on the standard limit of infinite dimensions but goes beyond that by treating inter-unit-cell interactions on an equal footing with intra-unit-cell ones. We then apply this approach to the extended Hubbard model. We identify a non-Fermi liquid state in this model. This novel state displays the intriguing phenomenon of spin-charge separation. |