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  • 1
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    Electronic, magnetic, and geometric structure of metallo-carbohedrenes (1992)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1992-12-04
    Description: The energetics and the electronic, magnetic, and geometric structure of the metallocarbohedrene Ti(8)C(12) have been calculated self-consistently in the density functional formulation. The structure of Ti(8)C(12) is a distorted dodecahedron with a binding energy of 6.1 electron volts per atom. The unusual stability is derived from covalent-like bonding between carbon atoms and between titanium and carbon atoms with no appreciable interaction between titanium atoms. The density of states at the Fermi energy is high and is derived from a strong hybridization between titanium 3d and carbon sp electrons. Titanium sites carry a small magnetic moment of 0.35 Bohr magneton per atom and the cluster is only weakly magnetic.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reddy, B V -- Khanna, S N -- Jena, P -- New York, N.Y. -- Science. 1992 Dec 4;258(5088):1640-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17742535" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Complementary active sites cause size-selective reactivity of aluminum cluster anions with water (2009)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2009-01-24
    Description: The reactions of metal clusters with small molecules often depend on cluster size. The selectivity of oxygen reactions with aluminum cluster anions can be well described within an electronic shell model; however, not all reactions are subject to the same fundamental constraints. We observed the size selectivity of aluminum cluster anion reactions with water, which can be attributed to the dissociative chemisorption of water at specific surface sites. The reactivity depends on geometric rather than electronic shell structure. Identical arrangements of multiple active sites in Al16-, Al17-, and Al18- result in the production of H2 from water.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roach, Patrick J -- Woodward, W Hunter -- Castleman, A W Jr -- Reber, Arthur C -- Khanna, Shiv N -- New York, N.Y. -- Science. 2009 Jan 23;323(5913):492-5. doi: 10.1126/science.1165884.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departments of Chemistry and Physics, Pennsylvania State University, University Park, PA 16802, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19164745" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Formation of Al13I-: evidence for the superhalogen character of Al13 (2004)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2004-04-03
    Description: Al13- is a cluster known for the pronounced stability that arises from coincident closures of its geometric and electronic shells. We present experimental evidence for a very stable cluster corresponding to Al13I-. Ab initio calculations show that the cluster features a structurally unperturbed Al13- core and a region of high charge density on the aluminum vertex opposite from the iodine atom. This ionically bound magic cluster can be understood by considering that Al13 has an electronic structure reminiscent of a halogen atom. Comparisons to polyhalides provide a sound explanation for our chemical observations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bergeron, Denis E -- Castleman, A Welford Jr -- Morisato, Tsuguo -- Khanna, Shiv N -- New York, N.Y. -- Science. 2004 Apr 2;304(5667):84-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departments of Chemistry and Physics, Pennsylvania State University, University Park, PA 16802, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15066775" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    Al cluster superatoms as halogens in polyhalides and as alkaline earths in iodide salts (2005)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2005-01-18
    Description: Two classes of gas-phase aluminum-iodine clusters have been identified whose stability and reactivity can be understood in terms of the spherical shell jellium model. Experimental reactivity studies show that the Al13I-x clusters exhibit pronounced stability for even numbers of I atoms. Theoretical investigations reveal that the enhanced stability is associated with complementary pairs of I atoms occupying the on-top sites on the opposing Al atoms of the Al13- core. We also report the existence of another series, Al14I-x, that exhibits stability for odd numbers of I atoms. This series can be described as consisting of an Al14I-3 core upon which the I atoms occupy on-top locations around the Al atoms. The potential synthetic utility of superatom chemistry built upon these motifs is addressed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bergeron, D E -- Roach, P J -- Castleman, A W Jr -- Jones, N O -- Khanna, S N -- New York, N.Y. -- Science. 2005 Jan 14;307(5707):231-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15653497" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Electronic Resource
    Electronic Resource
    Electronic structure and chemical bonding of 3d-metal dimers ScX, X=Sc–Zn (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 10738-10748 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic and geometrical structures of the ground and excited states of the homonuclear Sc2, mixed ScTi, ScV, ScCr, ScMn, ScFe, ScCo, ScNi, ScCu, and ScZn 3d-metal dimers and their anions have been calculated using the density functional theory with generalized gradient approximation for the exchange-correlation potential. The ground states of the neutral dimers are found to be 5Σu− (Sc2), 6Σ+ (ScTi), 7Σ+ (ScV), 4Σ+ (ScCr), 3Σ+ (ScMn), 2Δ(ScFe), 1Σ+ (ScCo), 2Σ+ (ScNi), 3Δ(ScCu), and 4Σ+ (ScZn). A natural bond analysis reveals an antiferrimagnetic spin coupling in the ground states of ScCr, ScMn, and ScFe. This is due to the electron transfer from Sc to the opposite atom and specific bond formations. While each dimer has a unique chemical bonding pattern, most curious is the localization of two 4s electrons at both atomic sites in the ground 5Σu− state of Sc2, which leads to formation of two lone pairs and the bonding scheme: (3d+3d)α3(4s+4s)β1. No appreciable sd hybridization is found for the ground states of the ScX dimers except for ScNi. Even though the electron affinities of the ScX dimers are relatively low and do not exceed 1 eV, each ScX− (except ScCo−) possesses at least two states stable towards detachment of an extra electron. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1373693
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  • 6
    Electronic Resource
    Electronic Resource
    Geometry, electronic structure, and energetics of copper-doped aluminum clusters (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 9792-9796 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using density functional theory and generalized gradient approximation for exchange-correlation potential, we have calculated the equilibrium geometries and energetics of neutral and negatively charged AlnCu (n=11,12,13,14) clusters. Unlike the alkali atom-doped aluminum clusters in the same size range, the copper atom resides inside the aluminum cluster cage. Furthermore, the 3d and 4s energy levels of Cu hybridize with the valence electrons of Al causing a redistribution of the molecular orbital energy levels of the Aln clusters. However, this redistribution does not affect the magic numbers of AlnCu clusters that could be derived by assuming that Cu donates one electron to the valence levels of Aln clusters. This behavior, brought about by the smaller size and large ionization potential of the copper atom, contributes to the anomalous properties of AlnCu− anions: Unlike AlnX− (X=alkali atom), the mass ion intensities of AlnCu− are similar to those of Aln−. The calculated adiabatic electron affinities are also in very good agreement with experiment. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1367381
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  • 7
    Electronic Resource
    Electronic Resource
    Dehydrogenation reactions in Mg+(H2O)n clusters (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 3540-3544 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Experimental observations of the effects of solvation on the dehydrogenation reaction of Mg+(H2O)n to produce MgOH+(H2O)n−1 are presented for n≤6. The reaction is seen to occur spontaneously at room temperature for n(approximately-greater-than)4. Ligand switching reactions are used to show the Mg+–OH bonds are stronger than Mg+H2O bonds. The results show the energy required to lose an H atom decreases with the number of water molecules attached because the magnesium changes oxidation state and this results in stronger interactions with the water ligands. Ab initio calculations are used to explain these observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466396
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  • 8
    Electronic Resource
    Electronic Resource
    Metallocarbohedrenes: A New Class of Metal-Carbon Assemblies (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 9446-9449 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100089a015
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  • 9
    Electronic Resource
    Electronic Resource
    Atomic and electronic structure of neutral and charged SinOm clusters (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 1245-1250 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using molecular orbital approach and the generalized gradient approximation in the density functional theory, we have calculated the equilibrium geometries, binding energies, ionization potentials, and vertical and adiabatic electron affinities of SinOm clusters (n≤6,m≤12). The calculations were carried out using both Gaussian and numerical form for the atomic basis functions. Both procedures yield very similar results. The bonding in SinOm clusters is characterized by a significant charge transfer between the Si and O atoms and is stronger than in conventional semiconductor clusters. The bond distances are much less sensitive to cluster size than seen for metallic clusters. Similarly, calculated energy gaps between the highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) of (SiO2)n clusters increase with size while the reverse is the norm in most clusters. The HOMO-LUMO gap decreases as the oxygen content of a SinOm cluster is lowered eventually approaching the visible range. The photoluminescence and strong size dependence of optical properties of small silica clusters could thus be attributed to oxygen defects. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476675
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  • 10
    Electronic Resource
    Electronic Resource
    Spin configuration of Gd clusters and thin films (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5542-5542 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Studies of the magnetism and structure of Gd clusters and surfaces will be presented.1 The spin configuration of a Gd13 cluster and the Gd(0001) surface has been examined using electronic structure calculations as well as a Heisenberg model. Structural calculations show that the ground-state geometry of the cluster has a hcp arrangement with a slightly reduced nearest-neighbor distance compared to bulk and an average moment of 7.8 μB/atom. The Heisenberg model is calculated using a Ruderman-Kittel-Kasuya-Yosida-like interaction. The effects of competing ferromagnetic and antiferromagnetic coupling for the nearest- and next-nearest neighbor interaction, respectively, is investigated. It is shown that for a range of interaction strengths the spins in the cluster assume a canted configuration. This effect leads to lower net magnetization of the cluster, and accounts for the anomalous low moments of Gdn clusters that have been experimentally observed. A similar model of the Gd(0001) surface agrees well with earlier spin resolved low-energy electron diffraction experiments from Gd/W(110), and spin resolved secondary electron spectroscopy studies of the surface magnetism of Gd grown on Y(0001) will be presented. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364654
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