Reference Values for the Cross Second Virial Coefficients and Dilute Gas Binary Diffusion Coefficients of the Systems (H2O + O2) and (H2O + Air) from First Principles

The cross second virial coefficients and dilute gas binary diffusion coefficients of water (H2O) in oxygen (O2) and air were predicted with high accuracy for temperatures up to 2000 K using statistical thermodynamics and the kinetic theory of polyatomic gases. For this purpose, we developed a new H2O–O2 intermolecular potential energy surface, which is based on high-level quantum-chemical ab initio calculations and represented analytically as a site–site potential function. To determine the cross second virial coefficient and the dilute gas binary diffusion coefficient of the (H2O + air) system, we combined the calculated values for the (H2O + O2) system with available first-principles results from the literature for the systems (H2O + N2), (H2O + Ar), and (H2O + CO2). The calculated property values for both systems agree satisfactorily with experimental data and form the sole basis of new reference correlations, which we provide here as well.