MOLECULAR MODEL FOR NUCLEATION OF WATER ON IONS

Heteromolecular nucleation of water on ions plays an important role in atmospheric condensation. Previous work on homogeneous nucleation suggests that a microscopic-molecular approach is required to successfully calculate nucleation rates. An attempt is initiated to develop a molecular theory of nucleation of water on ions. This approach uses molecular dynamics, the computer solution of Newton's equations, to model microclusters containing up to 29 water molecules and either a Cs** plus or F** minus ion. Using this molecular model the excess free energies of the clusters are calculated. It is shown that results are not adequately described by the classical model which treats these clusters as charged spheres surrounded by a uniform dielectrtic.