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  • Atomic, Molecular and Optical Physics  (6)
  • Polyamide  (2)
  • Wiley-Blackwell  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Relativistic density-functional studies of naked and ligated gold clusters (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 595-610 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electronic structure investigations on a broad range of gold compounds, including naked and ligated gold clusters, are reviewed. The calculations have been carried out with a recently introduced relativistic variant of the linear combination of Gaussian-type orbitals density-functional (LCGTO-DF) method which affords all-electron investigations for very large systems. The accuracy of the method will be evaluated for the gold dimer. Then the electronic structure of the naked cluster Au55 is studied, both in Ih and Oh symmetry. Nonrelativistic and relativistic results obtained by the present method are compared to those of the much simpler jellium model. Since triphenylphosphine is among the most common ligands in gold chemistry a series of mononuclear gold phosphine compounds MeAuPR3 with increasingly complex ligands PR3 (R = H, CH3, C5H6) is discussed. The calculations reveal the success and the limitations of simpler phosphines often employed as model ligands in theoretical studies. Some aspects of the phosphine gold interaction in these simpler compounds carry over to the main group element centered gold clusters. Thereby one arrives at a rationalization of the particularly high stability of the carbon-centered octahedral cluster cation [(R3PAu)6C]2+ as compared to the neighboring isoelectronic boron and nitrogen-centered clusters. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560520853
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  • 2
    Electronic Resource
    Electronic Resource
    Rotations, quaternions and double groups. By Simon L. Altmann, Clarendon Press, Oxford, 1986, 317 pp. (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 401-401 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560320310
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  • 3
    Electronic Resource
    Electronic Resource
    Toward a chemisorption cluster model using the LCGTO-Xα method: Application to Ni(100)/Na (1988)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 34 (1988), S. 275-285 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified cluster approach for modeling local chemisorption phenomena is suggested on the basis of the linear combination of Gaussian-type orbitals (LCGTO) Xα method. Contractions of the fitting bases are employed to take into account the reduced polarizability of a surface cluster and to access larger cluster sizes. Furthermore, embedding of a cluster in the surface is mimicked by Gaussian broadening of the one-electron levels leading to fractional occupation numbers via a self-consistently determined Fermi energy of the cluster. As a first application results are presented for the clusters NinNa (n = 5, 9, 17) modeling the low coverage limit of the chemisorption system Ni(100)/Na. Calculated bond length, binding energy, and induced “surface” dipole moment show fair agreement with experimental values, indicating a substantial covalent character of alkali bonding on transition metal surfaces even in the zero coverage limit.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560340832
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  • 4
    Electronic Resource
    Electronic Resource
    An INDO/S-CI treatment including spin-orbit interaction based on Rumer spin functions. Application to the hydrated cerium ion (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 545-555 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We examine the inclusion of spin-orbit effects within the Rumer configuration interaction technique and discuss its implementation in the spectroscopic version of the intermediate neglect of differential overlap model (INDO/S-CI). An efficient strategy for calculating excitation energies, transition moments, and Mulliken populations for Rumer-adapted functions is described. As an example, results are presented for the ground and excited states of the hydrated trivalent cerium ion [Ce(H2O)9]3+, which confirm the low energy assignments to 4ƒ → 5 d transitions split by some 10000 cm-1 through spin-orbit coupling and ligand field interaction. Comparisons are made between this technique and one that we have used previously that utilizes configuration interaction over double-group adapted linear combinations of determinants.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560400848
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  • 5
    Electronic Resource
    Electronic Resource
    Electronic and magnetic properties of organometallic clusters: From the molecular to the metallic state (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 44 (1992), S. 605-619 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have performed a linear combination of Gaussian-type orbitals, LCGTO, local density functional, LDF, calculations on a series of low- and high-nuclearity carbonylated Ni clusters and on their naked counterparts. We have found that while the bare Ni clusters do exhibit several features in common with the bulk metal, the low-nuclearity carbonylated clusters do not show any metallic behavior. Signs of a developing metallic character are found for high-nuclearity Ni cluster carbonyls where it is possible to distinguish between “surface” atoms, which are directly interacting with the ligand sphere, and “bulk” atoms, which are only interacting with other metal atoms. Through the analysis of the magnetic properties of these systems it is possible to formulate a general model which rationalizes both the metallic behavior of the free Ni clusters and the nonmetallic behavior in certain carbonylated Ni clusters. This model is based on the perturbations induced by the ligands on the electronic structure of the metal atoms in the cluster. © 1992 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560440854
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  • 6
    Electronic Resource
    Electronic Resource
    Reactive blending of polypropylene/polyamide-6 in the presence of tailor-made succinic anhydride-terminated oligopropene compatibilizersDedicated to honor the 70th birthday of Professor Dr. Dr. h.c. H.-J. Cantow. (1993)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 4 (1993), S. 465-474 
    Details
    ISSN: 1042-7147
    Keywords: Polypropylene ; Polyamide ; Blend ; Compatibilizer ; Ziegler-Natta catalysts ; Metallocene ; Maleic anhydride ; Graft copolymer ; Block copolymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Various anhydride-terminated isotactic and atactic oligopropenes of number average molecular weights ranging between 1,000 and 10,000 g/mole, prepared by maleinating vinylidene-terminated propene oligomers obtained with isospecific and nonstereospecific metallocene-based Ziegler-Natta catalysts, have been evaluated as blend compatibilizers of polypropylene/polyamide-6 (70 vol%/30 vol%) blends to study the role of blend compatibilizer molecular architecture. When added during processing, as shown by IR spectroscopic analysis, the anhydride-terminated oligopropenes react with the amine-terminated polyamide-6 to yield polypropylene-block-polyamide-6 in situ. Such block copolymers are efficient dispersing agents. While the polyamide dispersion in the polypropylene continuous phase is not affected by blend compatibilizer stereoregularities, both stiffness and yield stress as well as notched Charpy impact strength increase with increasing stereoregularities and molecular weights. With oligopropene molecular weights exceeding 1,150 g/mole, the average size of the dispersed polyamide microphases correlates with the volume fraction of the oligopropene-block-polyamide-6 blend compatibilizer and the dicarboxylic acid anhydride/amine molar ratio.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1993.220040710
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  • 7
    Electronic Resource
    Electronic Resource
    Anisotropic dispersion polymerization of N-(4-aminobenzoyl)-caprolactam in polymer melts (1994)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 282-286 
    Details
    ISSN: 1042-7147
    Keywords: Dispersion ; Microcomposite ; Polyamide ; Polyaramide ; Molecular composite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: When N-(4-aminobenzoyl)-caprolactam (PAC) is injected into polymer melts, dispersions of anisotropic polyaramide particles with average diameters of 100-400 nm and aspect ratios of 5-10 are formed within few minutes. At 200°C PAC dispersion polymerization yields caprolactam and predominantly poly(p-phenylenebenzamide), whereas with increasing polymerization temperatures PAC ring-opening polymerization accounts for the incorporation of 6-aminocaproic acid units into the polyaramide backbone. Covalent bond formation between microparticle surfaces and functional groups of the matrix polymer provides excellent interfacial adhesion and stabilizes the anisotropic polyaramide microparticle dispersions. This in situ PAC dispersion polymerization during melt processing, producing polyaramide-whisker reinforced thermoplastics, represents a versatile route to organic microcomposites exhibiting improved stiffness and strength.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1994.220050507
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  • 8
    Electronic Resource
    Electronic Resource
    Quantum size effects in hexagonal aluminum films (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 675-686 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The work functions and surface energies of Al(111) films ranging from one to seven layers thick have been calculated using the linear combinations of Gaussian type orbitals-fitting function (LCGTO-FF) technique, as implemented in the program package FILMS, an all-electron full-potential electronic structure method. Both quantities exhibit significant quantum size effect (QSE), in basic agreement with three previous investigations using more approximate techniques. However, there are significant quantitative differences among the four sets of results. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560520860
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