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 less than or equal to N less than or equal to 33, is carried out using an ab initio rigid molecule model, the Matsuoka-Clementi-Yoshimine p otential, and an empirical flexible molecule model, the Stillinger-Rahman p otential. 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 famil y can be thought of as formed from the aggregation of single units to some specific structures. In addition, the sequences present an apparent asympto tic behavior. (C) 1999 Elsevier Science B.V. All rights reserved.