Cross Second Virial Coefficient of the H2O–CO System from a New Ab Initio Pair Potential

Abstract The cross second virial coefficient $$B_{12}$$ B 12 for the interaction between water (H 2 O) and carbon monoxide (CO) was obtained with low uncertainty at temperatures from 200 K to 2000 employing a new intermolecular potential energy surface (PES) H O–CO system. This PES fitted energies determined about 58 000 configurations using high-level quantum-chemical ab initio methods up coupled cluster single, double, perturbative triple excitations [CCSD(T)]. extracted semiclassical approach. An accurate correlation of calculated values used determine dilute gas isothermal Joule–Thomson coefficient, $$\phi _{12}=B_{12}-T(\mathrm {d}B_{12}/\mathrm {d}T)$$ ϕ = - T ( d / ) . predicted both _{12}$$ agree reasonably well few existing experimental data older should be most estimates these quantities date.