EXAMINATION OF ADEQUACY OF 12-6-POTENTIAL FOR LIQUID ARGON BY MEANS OF MONTE CARLO CALCULATIONS

Monte Carlo calculations of thermodynamic properties of argon are reported for the temperature range between the triple point and the critical temperature at pressures up to 700 atm. It is shown that the Lennard-Jones 12-6 potential with the parameters proposed by Michels et al., viz., ε/k=119.8°K and σ=3.405 Å, leads to internal energies and pressures which are in fair agreement with the experimental values. The over-all agreement with experiment may be substantially improved by reducing the depth of the potential well to ε/k=117.2°K. The use of other potentials, the importance of nonadditivity corrections, and the agreement between the Monte Carlo results and those obtained by the method of molecular dynamics are briefly discussed.