We derive the non-retarded energy shift of a neutral atom for two different
geometries. For an atom close to a cylindrical wire we find an integral
representation for the energy shift, give asymptotic expressions, and
interpolate numerically. For an atom close to a semi-infinite halfplane we
determine the exact Green's function of the Laplace equation and use it derive
the exact energy shift for an arbitrary position of the atom. These results can
be used to estimate the energy shift of an atom close to etched microstructures
that protrude from substrates.Comment: 7 pages, 5 figure