1. Department of Chemical Engineering, Environmental Engineering Program, Yale University, P.O. Box 208286, New Haven, Connecticut 06520-8286, Theoretical Division, Los Alamos National Laboratory, Mail Stop: B284, Los Alamos, New Mexico 87545, and Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków, Poland