DFT modeling of successive hydrogenated subnano-size aluminum clusters

Abstract

Energies, structural and vibrational characteristics of isomers of step-wise hydrogenated aluminum clusters Al13Hn, Al44Hn and Al89Hn were calculated using the DFT B3LYP method and the evolution of the clusters with increasing number n of H atoms was followed. It is found that the geometry distortions of the clusters grow with rising n, becoming ultimate at the end of the series and resulting in complicated cooperative rearrangements. An increasing number of the surface atoms are shifted to the oversurface area and form external valence-unsaturated fragments like AlHn, Al2Hn, etc., together with a gradual disintegration of the subsurface layer and embedment of the subsurface atoms into the surface shell. The surface shells acquire 5- or 6-membered “windows” which can serve as “gates” for the migration of external H atoms into the inner cavity and the formation of nontrivial structures with internal H-bridging bonds.