Effective potential energies and transport cross sections for interactions of hydrogen and nitrogen

The interaction energies for N₂-He and N₂-H₂ are calculated by accurate ab initio methods. The virial coefficient and differential scattering cross section for N₂-H₂ are calculated; the theoretical results are compared with experimental data. The transport collision integrals for N₂-H₂ and N₂-N₂ interactions are calculated and tabulated; the results yield transport coefficients that compare well with measured data. Transport coefficients are found to be determined accurately from the interaction energies for a specific configuration of the molecule formed from the interaction partners. Comparisons with results of measurement and accurate calculations demonstrate that the transport properties of complex molecular interactions can be determined rapidly and fairly accurately from the interaction energies of simpler systems using combination rules for the short-range parameters of effective interaction energies and the coefficients for the long-range forces. The coefficients for a two-parameter temperature expansion of diffusion and viscosity are tabulated for a realistic universal potential-energy that is based primarily on the results of very accurate calculations of the He-He interaction energy.