HYBRID QUANTUM AND CLASSICAL MECHANICAL MONTE-CARLO SIMULATIONS OF THE INTERACTION OF HYDROGEN-CHLORIDE WITH SOLID WATER CLUSTERS

Monte Carlo simulations using a hybrid quantum and classical mechanica l potential were performed for crystal and amorphous like HCl(H2O)(n) clusters (n less than or equal to 24). The subsystem composed by HCl a nd one water molecule was treated within density functional theory and a classical force field was used for the rest of the system. Simulati ons performed at 200 K suggest that the energetic feasibility of HCl d issociation strongly depends on its initial placement within the clust er. An important degree of ionization occurs only if HCl is incorporat ed into the surface. We observe that local melting does not play a cru cial role in the ionization process. (C) 1997 Elsevier Science B.V.