Complete ab initio three-body nonadditive potential in Monte Carlo simulations of vapor-liquid equilibria and pure phases of argon

Complete ab initio three-body nonadditivity, including the short-range cont ributions, has been used for the first time in Monte Carlo simulations of l iquid, gas, and liquid-vapor equilibrium of argon. Very good overall agreem ent with experiment has been achieved for phase equilibrium parameters and pV data of pure phases. The importance of various three-body interaction co mponents has been assessed and their relationship to the liquid structure h as been investigated. Although the short-range contributions to the nonaddi tivity are quite large, cancellations occurring between these and other com ponents at the interatomic distances typical for the liquid make the total three-body nonadditive effect very similar to that given by a simple triple -dipole potential. Performance of the three-term virial equation of state i s assessed based on the results of simulations. (C) 2001 American Institute of Physics.