Atomic interactions in argon

Abstract

The potential energy function for interaction of two argon atoms is determined as closely as possible by fitting a multiparameter potential function to experimental data on molecular beam scattering and second virial coefficients, and to the known long-range interaction coefficients. These data are consistent with a range of potential functions between which gas transport properties do not enable a clear choice to be made. In particular, gas viscosities calculated with any of the potential functions show deviations from experiment which are tentatively ascribed to unexpectedly large slip in the viscosity measurements. Third virial coefficients calculated with allowance for the triple-dipole dispersion three-body interaction are close to experimental values whichever function is used, suggesting that other non-additive interactions must be small. Assuming this, the properties of crystalline argon at 0ºK are used to specify a single potential function.