  Using the SCRPA, we study the intersite interaction effect on the dynamics of
N electrons system. We have considered an extended Hubbard model including
intrasite and intersite interactions, and we have applied this model to a
system of two neighbouring atoms containing a free electron. The application of
SCRPA to this model allows us to study the intersite interaction effect on the
ground state and the excitation energies of system. We show that the repulsive
interaction between the electrons of the neighbouring atoms is the origin of an
supplementary conductivity of the system.
