Dielectric constant and density of states of the Drude-Lorentz model of a nonpolar fluid

The absorption spectrum and density of states of the Drude-Lorentz model of a nonpolar fluid are studied on the basis of a statistical theory. In the dilute limit the shift and broadening uf the spectral line and of the density of states, due to dipolar interactions, are described by universal scaling functions, which have been evaluated in a self-consistent ring approximation. At higher densities the lineshapes are influenced by structural effects. These are taken into account in a pair approximation. The theory agrees well with simulation data for semidilute fluids.