Transport Properties of Gases Obeying a Modified Buckingham (Exp-Six) Potential

Abstract

A large number of the Chapman and Cowling collision integrals have been calculated for gases obeying a modified Buckingham potential, $$\mathrm{[open\; phi](r)=}\frac{\epsilon }{\text{1−6/α}}\left[\frac{6}{\alpha }{e}^{{\text{α(1−r/r}}_m)}-{\left(\frac{r_m}{r}\right)}^6\right].$$ The results are tabulated over a large temperature range, kT / ε from 0 to 200, and for four values of the parameter α, 12, 13, 14, and 15. The treatment was entirely classical, and no corrections for quantum effects were made. The results should be applicable to most simple, nonpolar gases, and may be used to obtain information about intermolecular forces from the observed temperature dependence of gaseous transport properties. The second approximation to the thermal diffusion ratio and the third approximation to the coefficient of ordinary diffusion have been derived according to the method of Chapman and Cowling. Evaluation of the potential parameters for specific substances and applications of the results will be published later.