Molecular dynamics computer simulations were performed for (H2O)(n) (n=12, 16, and 20) followed by systematic quenching under a polarizable and a nonpolarizable model to determine the minimum energy structures each favored. Ab initio calculations were done on several minima for (H2O)(12) to determine their relative energies. The polarizable model prefers cagelike structures for all cluster sizes, whereas the nonpolarizable model predicts minima of fused cubes for (H2O)(12) and (H2O)(16) but makes the transition to a cagelike minimum at (H2O)(20).