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Hydrogen molecules adsorption and storage in Sc coated Si@Al12 cluster were investigated using density functional theory methods. Scandium atoms can bind strongly to the surfaces of Si@Al12 due to the charge transfer between Sc and Si@Al12, and do not suffer from clustering on the substrate. Si@Al12 cluster coated with three and four Sc atoms can adsorb 16 and 18 H2 molecules with a binding energy of 0.28–0.63 eV/H2, corresponding to hydrogen storage capacity of 6.0 and 6.3 wt %, respectively. The stable Si@Al12 can be applied as one of candidates for hydrogen storage materials at ambient conditions. [ABSTRACT FROM AUTHOR]

The studies on the structure and electronic properties of hydrogenated metal embedded Al12 cage clusters have been performed by density functional theory calculations. We have investigated aluminum cluster hydrides with 12 and 14 hydrogen atoms, respectively. Insertion of the Mg, Ca alkali metals remarkably enhances the stability of the aluminum clusters. The hydrogen atom prefers to occupy on-top sites along the surface of the clusters. Mulliken population analysis indicates that significant charge transfer occurs between the Mg and Ca atoms and the Al atoms. Our computations suggest that these clusters appear to be physically and chemically stable. [ABSTRACT FROM AUTHOR]

Extensive studies of structural and magnetic properties of pure Ni ( n=2-21) clusters are carried out using density functional theory with generalized gradient approximation. A new structural growth pattern is reported and the icosahedron sequence is not the global minima structures for size n < 16. The evolution pattern of Ni-Ni clusters is based on square pyramid. For cluster between n = 9 and n = 14, structures of them are trilayered stacking pattern. Especially for Ni, it seriously deviates from icosahedral pattern which was frequently assumed in previous studies. Ni, Ni and Ni are pieces of a double tetrahedron. For cluster size larger than 16, icosahedron based configurations are found to be the dominative structure pattern with exception of Ni. But trilayered structure is a strong competitor due to small difference in energy between this pattern and icosahedral family. The comparison of magnetic behavior between the calculations and experimental results are conducted. The average coordination mainly dominates on the magnetic behavior in the size range we considered. [ABSTRACT FROM AUTHOR]

We studied the structure and electronic properties of Al7OH clusters using density functional theory with generalized gradient approximation. OH prefers to the ontop site of Al atoms, and the hollow form is not stable. The Al7 moieties can keep their structures in ontop form Al7OH cluster, while it dramatically changes for bridge form ones. The binding strength between Al7 and OH are much larger than that of Al7I and Al7H. The bonding characteristic of Al7–OH is mainly ionic according to the population analysis. Large binding energy, HOMO–LUMO gap, and high ionization potential imply that Al7OH cluster is physically high and chemically stable. [ABSTRACT FROM AUTHOR]

Density functional theory has been employed in order to investigate the structure and stability of Si@Al12Hn ( $n=1\!\!-\!\!14$) clusters. Hydrogenated Si@Al12 clusters exhibit pronounced stability for even numbers of H atoms. Large binding energy, HOMO-LUMO gaps and increased ionization potentials imply that these clusters should be physically and chemically stable. The analysis of the charge density of the HOMO plot illustrates that a pair of hydrogen atoms prefer to occupy opposing on-top sites for clusters with an even n number. Studies of deformation charge density plots demonstrate that significant charge transfer occurs from the Si@Al12 to the H atoms. [ABSTRACT FROM AUTHOR]

The ground state structures of Co12X(X=Ni, Ag, Pt, Au) clusters are obtained by a genetic algorithm with a Gupta-like many-body potential, and further optimized using the density functional theory with generalized gradient approximation. The structures of Co12X have a slightly distorted icosahedral pattern. The X atom is on the surface for the most stable configuration. Their total magnetic moments are 0μB, 3μB, 21μB, and 22μB, respectively. The reasons for the reduction of magnetism of Co12X are discussed in detail. [ABSTRACT FROM AUTHOR]