Low-Density "Patches" in the Hydrogen-Bond Network of Liquid Water: Evidence from Molecular-Dynamics Computer Simulations

Abstract

The connectivity properties of liquid water are studied with molecular dynamics. It is found that the hydrogen-bonded network includes tiny spatially correlated "patches" of four-bonded molecules, and that the local density near a "patch" is lower than the global density. The diameter of the finite patches increases with decreasing temperature, and is comparable to the characteristic length scale of density fluctuations recently measured by small-angle x-ray scattering.