Characterization of water octamer, nanomer, decamer, and iodide-water interactions using molecular dynamics techniques

The lowest minimum-energy structures for the water octamer, nanomer, and de camer and the hydration of iodide were characterized using molecular dynami cs techniques and polarizable potential models of Dang and Chang [J. Chem. Phys. 106, 8149 (1997)]. The calculations predicted the two lowest-energy c ubic isomers, D-2d and S-4, for the water octamer. The lowest minimum-energ y structures for the nanomer and decamer were derived from the octamer by i nsertion of one and two water molecules, respectively, into the cubic isome rs. Our potential models provided an excellent description of the hydration of iodide in water clusters and in solution at room temperature. At 0 K, t he lowest energy-minimum structures predicted by our calculations are in ex cellent agreement with the available optimized structures obtained from acc urate electronic structure theory calculations for similar systems. In all cases, the surface states are dominant and the polarizability plays an impo rtant role in the hydration of iodide in water clusters at 0 K. (C) 1999 Am erican Institute of Physics. [S0021-9606(99)51803-5].