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The traditional method for opening the electron shells of noble gas atoms involves a strong electronegative atom or group. However, this approach is limited to only heavy noble-gas atoms, such as Kr and Xe. In this paper, we performed accurate calculations of He@C8H8 and He@C10H16 and showed the possibility of opening the electron shell of a light noble-gas atom. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The lowest-energy structures of medium-sized Li n (n=20, 30, 40, 50) clusters are determined from simulated annealing technique followed by geometry optimization within the framework of density functional theory. The shapes of magic-number Li20 and Li40 clusters are nearly spherical while those of the other clusters are ellipsoid. The growth of Li n clusters is based on core of multi-layered pentagonal bipyramids with other atoms capped on the surface. The binding energies of the Li n clusters were computed and compared with experiments. At magic-number sizes (n=20, 40), Li n clusters possess relatively larger HOMO–LUMO gaps and higher ionization potentials, corresponding to the closure of electron shell. The molecular orbitals of the lithium clusters can be grouped into electron shells and their spatial distributions resemble the atomic orbitals. The average polarizability of the Li clusters reduces rapidly with cluster size and can be approximately described by a classical metallic sphere model. The optical absorption spectra of Li n clusters from time-dependent density functional theory calculations show giant resonance phenomenon, and resonance peak blueshifts with increasing cluster size. [Copyright &y& Elsevier]

Fusion of two cages leading to M 2 Si 18 fused cage. [Display omitted] • Geometric structures of M 2 Si 11-18 change from a tubular shape to a cage and then a fused cage. • The fused cages M 2 Si 18 present a novel structural motif for silicon clusters. • The fused cages M 2 Si 18 arise from a fusion of both M@Si 10 and M@Si 12 prisms with addition of two Si atoms. • Formation and occupancy of electron shells contribute to the stabilization of fused cages. Geometries of doubly transition metal doped silicon clusters M 2 Si n , M 2 = Mo 2 , Nb 2 , Ta 2 , W 2 , NbMo, TaW were determined by DFT computations. Geometries of M 2 Si n in the range from 11 to 18 Si atoms change from a tubular shape to a cage and then a fused cage. The M 2 Si 18 sizes present us with a novel structural motif, the fused cage, for silicon clusters. Such fused cages arise from a fusion of both MSi 10 and MSi 12 prisms followed by addition of two Si atoms. Formation and filling of electron shells contribute to the high thermodynamic stability of M 2 Si 18 fused clusters. [ABSTRACT FROM AUTHOR]