We investigated the reaction between a sodium atom and water molecules in both
small and medium-size vibrationally excited water clusters using ab initio molecular
dynamics simulations. Formation of NaOH was observed in small (n = 4, 5) clusters,
while water dissociation and subsequent geminate recombination accompanied by a
transient formation of a Na+ - OH- pair occurred in a 34 water cluster. Our results
show that the initial step of the vibrationally excited reaction between a single
sodium atom and water does not shut off in larger clusters and that it can also
occur in the bulk water, however, more sodium atoms are likely required to stabilize
the product.