H-H-2 collision integrals and transport coefficients

The transport cross sections and collision integrals for H-H-2 interactions have been calculated from the results of accurate ab initio structure calculations using sudden scattering approximations. The low-temperature diffusion and viscosity coefficients agree well with the results of a close-coupling scattering calculation. The values calculated from the potential energies deduced from scattering measurements are in agreement with the theoretical results. The viscosity coefficients for H-H and H-2-H-2 have also been calculated; the H-2-H-2 results are very close to the measured data for temperatures in the range 200-400 K.