The Intermolecular Potentials for Some Simple Nonpolar Molecules

Abstract

Experimental data on the crystal properties, second virial coefficients, and viscosity coefficients of Ne, A, Kr, Xe, CH₄, N₂, CO, O₂, and CO₂ were analyzed for the purpose of obtaining values of the parameters in the exp‐six intermolecular potential, $\mathrm{[open\; phi](r)=}\frac{\epsilon }{\text{1−6/α}}\left[\frac{6}{\alpha }{e}^{{\text{α(1−r/r}}_m)}-{\left(\frac{r_m}{r}\right)}^6\right]$ . For gases whose molecules are spherical, it was possible to reproduce, with a single set of potential parameters, not only the crystal, second virial, and viscosity data, but also data on other transport properties with fair accuracy. For gases whose molecules deviate appreciably from spherical symmetry it was necessary to choose at least two different sets of potential parameters in order to reproduce different types of properties. Such behavior was taken to indicate the inadequacy of the assumptions, made in the fundamental gas theories, that intermolecular forces are central and that intermolecular collisions are elastic.