An equation of state for simple liquids

Abstract
An empirical formula for the Helmholtz free energy of a system of particles interacting through the Lennard-Jones 12-6 potential is derived on the basis of Monte Carlo computations of the internal energy and pressure. The calculations cover the reduced temperature range from [Ttilde] = 0·551 to [Ttilde] = 1·237 and reduced pressures up to [ptilde] = 1·6. The results are used to assess the adequacy of the 12-6 potential model for a number of simple liquids (Ar, Kr, Xe, CH4, N2, O2, CO) and values of the effective 12-6 potential parameters are proposed for each.