Molecular simulation of the vapour–liquid phase coexistence of neon and argon using ab initio potentials

Abstract

Gibbs ensemble simulations using ab initio intermolecular potentials are reported for the vapour–liquid phase coexistence of neon and argon. For neon two different quantum chemical ab initio potentials of well-known quality are used to investigate the effect of the quality of pair interactions. In addition calculations are also reported for neon using a potential that includes three-body interactions. For argon, simulations are compared with results obtained from NPH-ensemble molecular dynamics simulations. It is found that the results of a perfect pair potential must occur outside the experimental temperature–density phase envelope. Therefore, if a perfect pair potential is used, many-body interactions and quantum effects must be considered to obtain good agreement with experiment.