Ab initio electronic structure calculations have been performed using plane-wave ultrasoft pseudopotentials as well as Gaussian atomic-orbital methods to understand the interaction of hydrogen with aluminum clusters. Our results show large binding energies of a single hydrogen atom on small A1 clusters and large highest occupied and lowest unoccupied molecular-orbital gaps for AlH, Al7H, and Al13H making these species behave like magic clusters. In general the binding energy of H is found to decrease with an increase in the cluster size. Calculations on two hydrogen atoms on Al clusters show large binding energies for AlnH2 with n = 2, 4, 6, and 8, but a significant decrease for Al7H2 as compared to Al7H. These results confirm the magic behavior of Al7H and suggest that hydrogen should be dissociated on Al6, in excellent agreement with the available experimental data.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2002 Jan 15