Pivot method for global optimization: a study of water clusters (H2O)N with 2⩽N⩽33

By means of the pivot method, an optimization work on water clusters (H2O)N, with 2⩽N⩽33, is carried out using an ab initio rigid molecule model, the Matsuoka–Clementi–Yoshimine potential, and an empirical flexible molecule model, the Stillinger–Rahman potential. The results show that, under certain conditions, the pivot method algorithm is likely to yield optimized structures that are related to one another in such a manner that they form families. The structures in a family can be thought of as formed from the aggregation of single units to some specific structures. In addition, the sequences present an apparent asymptotic behavior.