The liquid-vapor equilibrium isotopic fractionation of water is determined by molecular-based simulation, via Gibbs ensemble Monte Carlo and isothermal-isochoric molecular dynamics involving two radically different but realistic models, the extended simple point charge, and the Gaussian charge polarizable models. The predicted temperature dependence of the liquid-vapor equilibrium isotopic fractionation factors for H2 O18 H2 O16, H2 O17 H2 O 16, and H2 H1 O16 2H 1 O16 are compared against the most accurate experimental datasets to assess the ability of these intermolecular potential models to describe quantum effects according to the Kirkwood-Wigner free energy perturbation h 2 -expansion. Predictions of the vapor pressure isotopic effect for the H2 O18 H2 O 16 and H2 O17 H2 O16 pairs are also presented in comparison with experimental data and two recently proposed thermodynamic modeling approaches. Finally, the simulation results are used to discuss some approximations behind the microscopic interpretation of isotopic fractionation based on the underlying rototranslational coupling.
|Journal||Journal of Chemical Physics|
|State||Published - 2009|