Do more strongly hydrogen-bonded water molecules reorient more slowly ?

We study how water OH reorientation dynamics’ short and long-time contributions depend on the hydrogen(H)-bond strength. The initial librational reorientation occurs within a cone. We show quantitatively that the stronger the H-bond, the smaller the cone angle and librational reorientation amplitude. The long-time decay is independent of the initial OH ⋯ O H-bond strength, as explained by our recently proposed molecular jump mechanism for the water reorientation mechanism: in the vast majority of (transient) H-bond breaking events, a new H-bond partner is unavailable and the reorientation is unsuccessful; successful reorientation requires this availability, which is independent of the H-bond strength.