Isotopic difference in the water second virial coefficient: a refined evaluation within non-rigid BJH- and MCY-type potentials

Abstract The BJH- and MCY-type water—water non-rigid potentials are used for evaluation of the isotopic difference in the second virial coefficient of light and heavy water. The potential energy term is adjusted to yield a best reproduction of the observed values of the energy difference. It has been found for the flexible potentials that the best fit requires a decrease of the energy-minimum depth. The decrease amounts to about 1 kJ/mol for the MCY-type flexible potentials and 2–6 kJ/mol for the BJH-type flexible potentials. The finding is consistent with recently suggested potential energy refinement adjusted to the observed dimerization equilibrium constants.