Ab initio intermolecular potential energy surface and thermophysical properties of nitrous oxide

Abstract

We present an analytical intermolecular potential energy surface (PES) for two rigid nitrous oxide (N₂O) molecules derived from high-level quantum-chemical ab initio calculations. Interaction energies for 2018 N₂O-N₂O configurations were computed utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory using basis sets up to aug-cc-pVQZ supplemented with bond functions. A site-site potential function with seven sites per N₂O molecule was fitted to the pair interaction energies. We validated our PES by computing the second virial coefficient as well as shear viscosity and thermal conductivity in the dilute-gas limit. The values of these properties are substantiated by the best experimental data.