On nuclear quantum effects and their effect on hydrogen bonds in water

Thomsen, B.  ; Shiga, Motoyuki   

Nuclear quantum effects (NQEs) are important for the description of the hydrogen bonds in water, and their inclusion in molecular dynamics simulations of the liquid state is therefore essential for the accurate modeling of the structure. This remains true even under the sub- and supercritical conditions, i.e. water in the liquid or fluid state at high temperature and under high pressure. The exchange of the protium to deuterium or tritium has a large effect on the size of the NQEs, as it is found that light water (HO) forms a more disordered liquid phase than that of heavy water (DO). For the mixed isotopologue species, HDO and HTO, dissolved in water we find a less structured hydration shells and fewer hydrogen bonds than in light water. The translational and rotational dynamics of heavy water are slowed down compared to light water, which is correlated with the extension of hydrogen bond lifetimes as protium is exchanged for deuterium.