A comparison between classical trajectory and infinite-order sudden calculations of transport and relaxation cross sections for N₂-Ne mixtures

Abstract

Classical trajectory calculations of effective cross sections have been carried out for the N₂-Ne system using the recent HFD3(N₂-Ne) potential surface of McCourt et al. Forty-five such cross sections governing a wide variety of transport and relaxation phenomena in binary gaseous mixtures have been calculated at a number of temperatures ranging from 77K to 1100K. Wherever possible, we have made comparisons with much cheaper infinite-order sudden approximation (IOSA) calculations in order to assess their reliability. For cross sections relating to diffusion and viscosity, IOSA errors are less than 5·4 per cent, but, for cross sections which vanish for isotropic interactions, the IOSA is much less reliable, with possible errors of up to a factor of two. At the same time, we have compared our classical trajectory results for this surface with available experimental results. We find that the HFD3(N₂-Ne) surface is too anisotropic, by as much as 20 per cent.