On the Problem of Criteria for Phase Transitions in Water Clusters (A Hexamer and Octamer Example)

The study concerns the dynamics of a network of hydrogen bonds in small water clusters (on the example of hexamer and octamer clusters). The numerical experiment is carried out with the molecular dynamics method using two analytical rigid potentials TIP4P and TIP5P. According to the obtained results, the criteria of phase transitions provided by the cluster theory are not reliable enough in the case of small water clusters. This is testified by the distributions of potential energies of individual molecules in the clusters. It is shown that the appearance of several peaks in these distributions reflects the number of hydrogen bonds between the molecule and other molecules of the cluster.