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We present, based on state of the art density functional theoretic calculations, a new putative ground state (GS) for the cluster (TiO2)10, which results more than 1 eV lower in energy than all those previously reported in the literature. The geometric and electronic properties of this new cluster are discussed in detail and in comparison with the rest. We analyze the implications of the new GS in the context of recent experiments of reactivity regarding oxygen exchange with gaseous CO2 in TiO2 nanostructures, and also in connection with a recent interpretation of photoelectron spectroscopic measurements of the band gap of gas phase TiO2- clusters. [ABSTRACT FROM AUTHOR]

Recently, Ar physisorption was used as a structural probe for the location of the Ti dopant atom in aluminium cluster cations, AlnTi+ [Lang et al., J. Am. Soc. Mass Spectrom. 22, 1508 (2011)]. As an experiment result, the lack of Ar complexes for n > nc determines the cluster size for which the Ti atom is located inside of an Al cage. To elucidate the decisive factors for the formation of endohedrally AlnTi+, experimentalists proposed detailed computational studies as indispensable. In this work, we investigated, using the density functional theory, the structural and electronic properties of singly titanium doped cationic clusters, AlnTi+ (n = 16–21) as well as the adsorption of an Ar atom on them. The first endohedral doped cluster, with Ti encapsulated in a fcc-like cage skeleton, appears at nc = 21, which is the critical number consistent with the exohedral-endohedral transition experimentally observed. At this critical size the non-crystalline icosahedral growth pattern, related to the pure aluminium clusters, with the Ti atom in the surface, changes into a endohedral fcc-like pattern. The map of structural isomers, relative energy differences, second energy differences, and structural parameters were determined and analyzed. Moreover, we show the critical size depends on the net charge of the cluster, being different for the cationic clusters (nc = 21) and their neutral counterparts (nc = 20). For the AlnTi+ · Ar complexes, and for n < 21, the preferred Ar adsorption site is on top of the exohedral Ti atom, with adsorption energy in very good agreement with the experimental value. Instead, for n = 21, the Ar adsorption occurs on the top an Al atom with very low absorption energy. For all sizes the geometry of the AlnTi+ clusters keeps unaltered in the Arcluster complexes. This fact indicates that Ar adsorption does not influence the cluster structure, providing support to the experimental technique used. For nc = 21, the smallest size of endohedral Ti doped cationic clusters, the Ar binding energy decreases drastically, whereas the Ar-cluster distance increases substantially, point to Ar physisorption, as assumed by the experimentalists. Calculated Ar adsorption energies agree well with available experimental binding energies. [ABSTRACT FROM AUTHOR]

An analytic expression for the total energy of 4He clusters composed of N atoms is obtained by means of a variational solution of the energy density functional. The energy is calculated as an expansion in decreasing powers of the cluster radius, R∝N1/3. Contributions of volume (R3), surface (R2), curvature (R), constant (R0), (1/R), and (1/R2) are clearly separated in the formula. Chemical potentials, fusion and fission potentials, surface thickness, and unit radii are also obtained. [ABSTRACT FROM AUTHOR]

Presents a study which calculated the local magnetic moments and magnetic orders for a Fe(Cr) monolayer adsorbed on a stepped Cr(Fe)(107) substrate. Results obtained; Presentation of two magnetic arrangements obtained for Cr/Fe(107); Magnetic moment in units of µg per atom.