Shellvation of the ammonium cation by molecular hydrogen: a theoretical study

The results of the theoretical study of NH4+(H-2)(n), (n = 1-8) clusters ar e presented. Two shells for ligand binding which are characterized by the v ertex or face binding of H-2 to the NH4+ tetrahedron were determined. The m ain difference in the nature of interactions observed in the structurally d ifferent complexes comes from the electrostatic interactions. The dispersio n energies are found to be less dependent on the geometry of the complex or on the charge of the core. The properties investigated such as dissociatio n energy and enthalpy, electronic density distribution and stretching vibra tions of H-2 are similar for molecules occupying the same shell and are sig nificantly different when neighboring shells are compared. (C) 2001 Publish ed by Elsevier Science B.V.