CUBE TO CAGE TRANSITIONS IN (H2O)(N) (N=12, 16, AND 20)

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 p refers cagelike structures for all cluster sizes, whereas the nonpolar izable model predicts minima of fused cubes for (H2O)(12) and (H2O)(16 ) but makes the transition to a cagelike minimum at (H2O)(20). (C) 199 6 American Institute of Physics.