Effects of the dispersion interaction in liquid water

The properties of liquid water obtained from molecular simulations using a density functional theory (B3LYP) based force field [O. Akin-Ojo, F. Wang, J. Comput. Chem. 32 (2011) 453.] with and without an intermolecular dispersion interaction term are compared. Although it is small, the dispersion interaction is found to significantly affect some properties such as the density and the heat of vaporization but not others, for example, the atom–atom radial distribution functions and the infrared spectra. The inclusion of the dispersion interaction in the force field produces an increase in the computed self diffusivity comparable to that resulting from a ∼5 K rise in temperature.