A SIMPLE 2-STRUCTURE MODEL FOR LIQUID WATER

Using no adjustable parameters but only known data on ice and on water dimers in the gas phase, it has been possible for the first time to construct a model involving isomerization between clusters which reproduces (+/- 2%) the anomalous heat capacity of liquid water from 0 to 100-degrees-C. The clusters are a polycyclic, cubic-shaped octamer which can dissociate into two cyclic tetramers. These clusters are held together by H bonds and though very labile appear to be the principal species present in liquid water. Polycyclic decamers and monocyclic pentamers may also exist and play a similar role. It is shown that a random H bond breaking model cannot account for the heat capacity of water.