MANY-BODY EFFECTS IN MOLECULAR-DYNAMICS SIMULATIONS OF NA+(H2O)N AND CL-(H2O)N CLUSTERS

Many-body effects were examined in a series of molecular dynamics computer simulations on the ionic aqueous clusters Na+ (H2O)n (n = 4,5,6,14) and Cl- (H2O)n (n = 4,5,6,7,8,14). Two potential models were used in the simulations. In one model (TIP4P) the potential was pairwise additive, while in the second model (SPCE/POL) the many body effects were explicitly included through a self-consistent polarization routine. The two models produce equilibrium structures which are significantly different in energy and geometry. The SPCE/POL model consistently predicts energetically more stable products. In addition, for the anion cluster systems the SPCE/POL model places the Cl- on the surface of the water cluster.