Many-body correlations in the interaction-induced light scattering from liquid CS2

Abstract

Additional information concerning the interaction-induced contribution to the intensities in depolarized light scattering spectra of liquid carbon disulfide is presented here. This was obtained from molecular dynamics computer simulations of relevant time-correlation functions (TCFs) along the gas-liquid coexistence curve. The interaction-induced part of the polarizability was evaluated assuming a first-order dipole-induced dipole mechanism. The simulated spectral TCFs for this system show coupled rotation-translation dynamics that are due in part to the nonspherical molecular shape of CS2 and in part to the orientation dependence of the dipole-induced polarizability Π. By writing Π in the usual way as the sum of a diagonal orientation-independent term plus a second-rank tensor in the polarizability anisotropy, the TCFs can be split into terms with varying degrees of orientation dependence. In addition, the collective TCFs were broken down into their component 2-, 3- and 4-body parts. The component parts of both the pure interaction-induced (II) and the cross (CR) TCFs between the II polarizabilities and the orientation (OR) variable were evaluated. At the highest densities, it is shown that the cancellation of II TCFs at short times is not as complete as for other simple molecules even though there is nearly a perfect cancellation of the 2- and 4-body correlations by negative 3-body terms in the long time limit.