  In this paper, effect of dipole-dipole interactions on nonlinear optical
properties of the system of randomly located semiconductor nanoparticles
embedded in bulk dielectric matrix is investigated. This effect results from
the nonzero variance of the net dipole field in an ensemble. The analytical
expressions describing the contribution of the dipole-dipole coupling to
nonlinear dielectric susceptibility are obtained. The derived relationships are
applicable over the full range of nanoparticle volume fractions. The factors
entering into the contribution and depending on configuration of the dipoles
are calculated for several cases. It is shown that for the different
arrangements of dipole alignments the relative change of this contribution does
not exceed 1/3.
