Determination of a Three Parameter Pair Potential from Second Virial Coefficients: Ar, Kr, and Xe

Abstract

To prepare second virial coefficient data for use in determining the Ar, Kr, and Xe pair potentials, random errors in B(T) data are initially eliminated by least square fitting to a polynomial in T −1. After choosing an analytical form for the potential, optimum values for the potential parameters are obtained using a modified version of the method of selected points. This procedure permits rapid testing of three parameter model potentials without having extensive tables of reduced second virial coefficients. A piecewise potential (RMMV for rigid, Morse, Mie, and van der Waals) was selected and extensively compared with existing theoretical and experimental determinations of the pair potential for Ar, Kr, and Xe. The RMMV potential was found to be satisfactory, not only in the well region, but also in the short and long range limits.