The structuredness of water at elevated temperatures along the saturation line

The structuredness of water is described quantitatively by several parameters over its existence as a liquid, along the saturation line, 0 to 374 °C. One is the number of intact hydrogen bonds, obtained from the ratio of the differences of the condensation Gibbs free energies of H₂O and D₂O, Δ^DHΔG_w*) and their hydrogen bond energies, estimated from spectroscopic data, Δε_DH. Other measures are the Kirkwood dipole orientation correlation parameter, g, the heat capacity density, corrected for that of the vapor, [C_p(1) - C_p(ig)]/V, the entropy deficit, ΔΔ_vapS°/R, relative to the vapor and an unstructured liquid, and the excess of the cohesive energy density over the internal pressure, [Δ_vapH° - R TJ/V - P_i All these measures point to a gradual decrease of the structuredness of liquid water as the temperature increases, but to an appreciable amount of structure remaining up to the critical point.