Nuclear quantum effects in water and its isotopologous from ab initio path integral molecular dynamics

Thomsen, B.  ; 志賀 基之   

Thomsen, B.; Shiga, Motoyuki

We report the structure and dynamics of ambient water and its isotopologues including nuclear quantum effects (NQEs) using ab initio path integral methods. For the pure isotopologues, light (HO(l)) and heavy (DO(l)) water, and TO(l), we find that the heavier isotopologues are more ordered due to more hydrogen bonds being formed in the heavier isotopologues liquid phases. The mixed isotope species, HDO(aq) and HTO(aq), have less structured hydration shells and form fewer hydrogen bonds than HO(l). This can be attributed to the relative compactness and asymmetry of the mixed isotope species, which results in a lower dipole moment when compared to that of the pure species. The translational and rotational dynamics of HO(l) and DO(l) are slowed down by the inclusion of NQEs in the simulations, which is correlated with an extension of hydrogen bond lifetimes in simulations including NQEs.