  We study the optical properties of gold nanoparticles coated with a nematic
liquid crystal whose director field is distributed around the nanoparticle
according to the anchoring conditions at the surface of the nanoparticle. The
distribution of the nematic liquid crystal is obtained by minimization of the
corresponding Frank free-energy functional whilst the optical response is
calculated by the discrete-dipole approximation. We find, in particular, that
the anisotropy of the nematic liquid-crystal coating does not affect much the
(isotropic) optical response of the nanoparticle. However, for strong anchoring
of the nematic liquid-crystal molecules on the surface of nanoparticle, the
inhomogeneity of the coating which is manifested by a ring-type singularity
(disclination or Saturn ring), produces an enhancement of the extinction cross
spectrum over the entire visible spectrum.
