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

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