Water anomalies and the double-well Takahashi model Original Research Article

Water in its liquid state has many anomalous properties. It is only recently that a molecular-level explanation of these anomalies was discovered through recognition that a thermal competition takes place between the inner and outer second-neighbor structure in liquid water. This essential feature, which sets water off from all other liquids, is captured here in a double-well Takahashi model. The availability of an exact solution of this model allows one to understand how the various anomalies arise as the temperature and pressure of the system are varied. It is expected that this study will give useful leads in future computer molecular dynamics studies of real water using new water potentials that take into account this important outer structure characteristic.