Theoretical Modeling of Stepwise Addition of H 2 Molecules to Magnesium Clusters Mg 18 and Mg 17 Ni

The potential energy surface (PES) along minimum energy paths of elementary hydrogenation reactions Mg 18 + H 2 → Mg 18 H 2 and Mg 17 Ni + H 2 → Mg 17 NiH 2 + H 2 → Mg 17 NiH 4 + H 2 → Mg 17 NiH 6 has been calculated by the density functional theory method. Local PES minima in the vicinity of low-lying isomers, intermediates, and transition states have been determined, and their energies, geometries, and spectroscopic parameters have been calculated. The effect of the Ni dopant on the energies and activation barriers of these reactions has been examined, depending on the position of the dopant on the surface and inside the internal cavity of the Mg 17 cage.