Estimated Collision Integrals for the Exponential Attractive Potential

Abstract

Collision integrals for the exponential attractive potential φ(r) = −A exp(−r/ρ) have been estimated from the known integrals for the inverse power attractive potentials φ(r) = −ar⁻ⁿ. The exponential attractive potential should be suitable for interactions between atoms or free radicals corresponding to bound molecular states, provided the temperature is not too high. Integrals for calculating the first Chapman‐Enskog approximation to the coefficients of viscosity, thermal conductivity, and diffusion have been estimated. The auxiliary functions A*, B*, and C*, which are required to calculate the coefficients of viscosity, thermal conductivity, and thermal diffusion in gas mixtures, are also tabulated. There is no simple way of assessing the accuracy of these estimates; however, when the same method is applied to the exponential repulsive potential, the estimated integrals agree with rigorously computed values to within 5% or better.