A molecular dynamics simulation of fluid hydrogen chloride

Abstract

We report a molecular dynamics computer simulation study of hydrogen chloride in the liquid and dense gas states. The intermolecular pair potential model consists of four cut off, shifted-force atom-atom Lennard-Jones (LJ) interactions, to which are added molecular electric point dipolar and quadrupolar interaction terms. The LJ parameters are fixed using the experimental density and vapour pressure of the coexisting liquid. The simulation is used to predict the internal energy and the self-diffusion coefficient for the liquid, and the internal energy and pressure for the supercritical fluid. Good agreement is obtained with experiment for these properties, and the model gives somewhat better results than those found in a previous study [2] in which the electrostatic forces were omitted. The mean squared torque for the liquid is now somewhat larger rather than smaller than the experimental value. We also calculate the site-site correlation functions and partial structure factors, and find in particular that the addition of the electrostatic forces has a large effect on the HH intermolecular pair correlations. Quantum corrections are calculated for the thermodynamic properties, and are larger than for the case where electrostatic forces are omitted but still constitute a small correction.