Ab initio intermolecular potential energy surface for the CO2-N2 system and related thermophysical properties

Abstract

A four-dimensional potential energy surface (PES) for the interaction between a rigid carbon diox- ide molecule and a rigid nitrogen molecule was constructed based on quantum-chemical ab initio calculations up to the coupled-cluster level with single, double, and perturbative triple excitations. Interaction energies for a total of 1893 points on the PES were calculated using the counterpoise- corrected supermolecular approach and basis sets of up to quintuple-zeta quality with bond functions. The interaction energies were extrapolated to the complete basis set limit, and an analytical site–site potential function with seven sites for carbon dioxide and five sites for nitrogen was fitted to the interaction energies. The CO 2 −− N 2 cross second virial coefficient as well as the dilute gas shear vis- cosity, thermal conductivity, and binary diffusion coefficient of CO 2 −− N 2 mixtures were calculated for temperatures up to 2000 K to validate the PES and to provide reliable reference values for these important properties. The calculated values are in very good agreement with the best experimental data.