THE EQUATION OF STATE OF SOFT REPULSIVE SPHERICAL MOLECULES

A non-perturbational method is proposed by which the compressibility factors of ensembles of soft repulsive spheres can be estimated. A distribution function for the effective collision diameter is derived from the Maxwell velocity distribution. This distribution function is used in connection with an equation of state for hard-sphere mixtures to calculate the thermodynamic properties of soft repulsive spheres. The predicted compressibility factors are compared to the results of the Weeks-Chandler-Andersen perturbation theory and Monte Carlo simulation. The new method, which does not require explicit information about radial distribution functions, agrees reasonably well with the simulation results.