ELSEVIER Physica A 233 (1996) 742-753
Patterns of hydrogen bonding in water and ice
Department of Physics, Faculty of Science, Australian National University,
Canberra ACT 0200, Australia
The six-vertex lattice model is augmented with ionic vertices and bonding defects. These
represent sources and sinks for hydrogen atoms, and the extra vertices account for the pH of
water. This 14-vertex lattice model with Bjerrum bond defects represents a not unrealistic model
of ice, and possibly also of structured water next to a surface. Such surfaces polarise the adjacent
molecules, which greatly restricts the possible patterns of hydrogen bonds. The polarisation is
screened by the defective vertices and bonds, which leads to a strong exponentially decaying
repulsion between two similar surfaces. The model is solved in mean field approximation, and
the relevance to the experimentally measured hydration forces is discussed.
The unique properties of water are due to the extensive network of hydrogen bonds,
with, at any instant, each molecule of the liquid on average correctly bonded to three
others. The pattem of bonds is, of course, much better defined in ice, where Bjerrum
L and D bond defects (none or two hydrogens on a bond) are comparatively rare.