Temperature-Dependent Hydrogen-Bond Geometry in Liquid Water

We have determined the hydrogen-bond geometry in liquid water from 0 to $80°\mathrm{C}$ by combining measurements of the proton magnetic shielding tensor with ab initio density functional calculations. The resulting moments of the distributions of hydrogen-bond length and angle are direct measures of thermal disorder in the hydrogen-bond network. These moments, and the distribution functions that can be reconstructed from them, impose quantitative constraints on structural models of liquid water.