RigidH2O Molecule Model of Anomalous Thermal Expansion of Ices

Structural details of hexagonal $\mathrm{I}h$ and cubic $\mathrm{I}c$ ices, resulting from a combination between ${\mathrm{H}}_2$O molecular and ice-lattice dimensions, reveal new features of the proton dynamics in hydrogen bonds, applicable to all aggregates of water molecules. Coupling of proton transfers with reorientations of molecules induce systematic changes in the hydrogen-bond dimensions, e.g., a shortening of the $\mathrm{O}\cdots \mathrm{O}$ distances, and an anomalous thermal expansion of the ice crystals about 80 K.