ABSTRACT
Many of the anomalous properties of liquid water nd their origin in the large number of directional hydrogen-bond interactions present in this liquid [1]. The extremely high density of hydrogen bonds leads to a strong cohesion between the water molecules with the result that water has an anomalously high freezing and melting point in view of its small molecular mass. The high density of hydrogen bonds also explains the high heat capacity of water: the breaking of the high density of hydrogen bonds requires an extremely large amount of energy. As a result, water is an ideal thermal regulator as the release or acceptance of large amounts of energy only leads to moderate changes of the temperature [2,3]. When water is frozen to ice, the water molecules form an extended spatial hydrogen-bonded network due to the strongly directional character of the hydrogen bonds and the bend shape of the water molecule. As a result, the specic volume increases at the phase transition to ice, which is probably the best known anomaly of water.
