Density dependent structural properties of dilute mixtures of OCS with argon. A molecular dynamics investigation

Abstract

Molecular dynamics simulation was used to study the intermolecular structure of carbonyl sulphide (OCS) diluted in argon at different densities and at room temperature. The intermolecular interactions between argon and OCS were investigated and an accurate effective atom-atom pairwise additive Lennard-Jones potential was proposed. The interaction model predicts a non-linear, T-shaped dimer structure in excellent agreement with experiment. The center of mass and the relevant site-site pair correlation functions, self-diffusion coefficients, and thermodynamic properties of the molecular system were calculated and analyzed. At low densities we found the nearest configuration to be maximal 1 argon with a nearly T-shaped (1:1) structure located on the CO bond. At higher densities this configuration is extended to maximal 2 or 3 argon atoms. The local structure has been discussed in the sense of its estimated duration (0.4–0.6 ps). This reflects the existence of transient “molecular clusters”.