Author: K. H. Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages : 74
Book Description
The electronic structures of small copper, nickel, palladium, and platinum clusters having simple-cubic and cubo-octahedral geometries have been calculated, using the self-consistent-field X-alpha scattered-wave approach to molecular-orbital (MO) theory. As the cluster size and coordination number are increased, the MO results show increasing similarity to the electronic structures of the corresponding crystalline metals. The calculated ionization potentials decrease gradually with increasing cluster size and for the 13-atom cubo-octahedral clusters are approximately 2 eV greater than the corresponding average bulk work functions. Localized d-electron states are also observed for the cubo-octahedral transition-metal clusters. They appear to be cluster analogs of the 'surface states' postulated for crystalline transition metals and probably play an important role in the chemisorption and catalytic activities of small metal aggregates of the type utilized as the active centers of heterogeneous catalysts. The SCF-Xalpha-SW MO results for transition-metal clusters are critically compared with those obtained for similar clusters by the extended-Huckel (EH) and complete-neglect-of-differential-overlap (CNDO) methods. The implications of these results in surface-cluster studies of chemisorption on transition metals are discussed.
Molecular-Orbital Studies of Transition- and Noble-Metal Clusters by the SCF-X(alpha) Scattered-Wave Method
Author: K. H. Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages : 74
Book Description
The electronic structures of small copper, nickel, palladium, and platinum clusters having simple-cubic and cubo-octahedral geometries have been calculated, using the self-consistent-field X-alpha scattered-wave approach to molecular-orbital (MO) theory. As the cluster size and coordination number are increased, the MO results show increasing similarity to the electronic structures of the corresponding crystalline metals. The calculated ionization potentials decrease gradually with increasing cluster size and for the 13-atom cubo-octahedral clusters are approximately 2 eV greater than the corresponding average bulk work functions. Localized d-electron states are also observed for the cubo-octahedral transition-metal clusters. They appear to be cluster analogs of the 'surface states' postulated for crystalline transition metals and probably play an important role in the chemisorption and catalytic activities of small metal aggregates of the type utilized as the active centers of heterogeneous catalysts. The SCF-Xalpha-SW MO results for transition-metal clusters are critically compared with those obtained for similar clusters by the extended-Huckel (EH) and complete-neglect-of-differential-overlap (CNDO) methods. The implications of these results in surface-cluster studies of chemisorption on transition metals are discussed.
Publisher:
ISBN:
Category :
Languages : en
Pages : 74
Book Description
The electronic structures of small copper, nickel, palladium, and platinum clusters having simple-cubic and cubo-octahedral geometries have been calculated, using the self-consistent-field X-alpha scattered-wave approach to molecular-orbital (MO) theory. As the cluster size and coordination number are increased, the MO results show increasing similarity to the electronic structures of the corresponding crystalline metals. The calculated ionization potentials decrease gradually with increasing cluster size and for the 13-atom cubo-octahedral clusters are approximately 2 eV greater than the corresponding average bulk work functions. Localized d-electron states are also observed for the cubo-octahedral transition-metal clusters. They appear to be cluster analogs of the 'surface states' postulated for crystalline transition metals and probably play an important role in the chemisorption and catalytic activities of small metal aggregates of the type utilized as the active centers of heterogeneous catalysts. The SCF-Xalpha-SW MO results for transition-metal clusters are critically compared with those obtained for similar clusters by the extended-Huckel (EH) and complete-neglect-of-differential-overlap (CNDO) methods. The implications of these results in surface-cluster studies of chemisorption on transition metals are discussed.
SCF-X Alpha-SW Cluster Molecular-Orbital Models of Catalysts, Alloys, Magnetic Materials, and Superconductors
Author: K. H. Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages : 50
Book Description
Recent self-consistent-field Xalpha scattered-wave (SCF-Xalpha-SW) molecular orbital studies of the electronic structures, chemical bonding, and related (e.g. catalytic, magnetic, and superconducting) properties of metal and alloy clusters are reviewed, including results for: (1) Li clusters, (2) Cu, Ni, Pd, and Pt clusters, (3) relativistic contributions to cluster electronic structure, (4) the interaction of hydrogen with Ni, Pd, and Pt clusters, (5) metal-support (Pt-SiO2 and Ru-SiO2) interactions, (6) magnetism of Fe clusters, (7) cluster of models of transition-metal impurities and their magnetic properties in copper and aluminum hosts, (8) cluster models of intermetallic compounds and solid-solution alloys, (9) cluster models of amorphous alloys, and (10) cluster molecular-orbital models of superconductors. (Author).
Publisher:
ISBN:
Category :
Languages : en
Pages : 50
Book Description
Recent self-consistent-field Xalpha scattered-wave (SCF-Xalpha-SW) molecular orbital studies of the electronic structures, chemical bonding, and related (e.g. catalytic, magnetic, and superconducting) properties of metal and alloy clusters are reviewed, including results for: (1) Li clusters, (2) Cu, Ni, Pd, and Pt clusters, (3) relativistic contributions to cluster electronic structure, (4) the interaction of hydrogen with Ni, Pd, and Pt clusters, (5) metal-support (Pt-SiO2 and Ru-SiO2) interactions, (6) magnetism of Fe clusters, (7) cluster of models of transition-metal impurities and their magnetic properties in copper and aluminum hosts, (8) cluster models of intermetallic compounds and solid-solution alloys, (9) cluster models of amorphous alloys, and (10) cluster molecular-orbital models of superconductors. (Author).
Scientific and Technical Aerospace Reports
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 978
Book Description
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 978
Book Description
Proceedings of the International Symposium on Atomic, Molecular, and Solid-State Theory, Collision Phenomena, and Computational Methods, Held at Flagler Beach, Florida, March 12-18, 1978
Author: Per-Olov Löwdin
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 582
Book Description
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 582
Book Description
Government Reports Index
Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 864
Book Description
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 864
Book Description
Government reports annual index
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 852
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 852
Book Description
Molecular Orbitals and the Atomistics of Fracture
Author: M. E. Eberhardt
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Self-consistent-field Xalpha scattered-wave (SCF-Xa-SW) cluster molecular-orbital models have been constructed for grain-boundary embrittlement of metals. Two specific examples are presented: (1) the embrittlement of nickel by sulfur and (2) the embrittlement of iron by hydrogen. (Author).
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Self-consistent-field Xalpha scattered-wave (SCF-Xa-SW) cluster molecular-orbital models have been constructed for grain-boundary embrittlement of metals. Two specific examples are presented: (1) the embrittlement of nickel by sulfur and (2) the embrittlement of iron by hydrogen. (Author).
Local Density Approximations in Quantum Chemistry and Solid State Physics
Author: Jens Peder Dahl
Publisher: Springer Science & Business Media
ISBN: 1489921427
Category : Science
Languages : en
Pages : 848
Book Description
The· simplest picture of an atom, a molecule or a solid is the picture of its distribution of charge. It is obtained by specifying the positions of the atomic nuclei and by showing how the density, p(E), of the electronic charge-cloud varies from place to place. A much more detailed picture is provided by the many-electron wavefunction. This quantity shows not only the arrangement of the electrons with respect to the nuclei, but also the arrangement of the electrons with respect to each other, and it allows the evaluation of the total energy and other properties. The many-electron wavefunction is in principle obtained by solving the many-electron Schrodinger equation for the motion of the interacting electrons under the influ ence of the nuclei, but in practice the equation is unsolvable, and it is necessary to proceed by methods of approximation. Needless to say, .such methods will as a rule depend on the complexity of the system considered.
Publisher: Springer Science & Business Media
ISBN: 1489921427
Category : Science
Languages : en
Pages : 848
Book Description
The· simplest picture of an atom, a molecule or a solid is the picture of its distribution of charge. It is obtained by specifying the positions of the atomic nuclei and by showing how the density, p(E), of the electronic charge-cloud varies from place to place. A much more detailed picture is provided by the many-electron wavefunction. This quantity shows not only the arrangement of the electrons with respect to the nuclei, but also the arrangement of the electrons with respect to each other, and it allows the evaluation of the total energy and other properties. The many-electron wavefunction is in principle obtained by solving the many-electron Schrodinger equation for the motion of the interacting electrons under the influ ence of the nuclei, but in practice the equation is unsolvable, and it is necessary to proceed by methods of approximation. Needless to say, .such methods will as a rule depend on the complexity of the system considered.
NBS Special Publication
Author:
Publisher:
ISBN:
Category : Weights and measures
Languages : en
Pages : 400
Book Description
Publisher:
ISBN:
Category : Weights and measures
Languages : en
Pages : 400
Book Description
Chemistry and Physics of Solid Surfaces
Author: Ralf Vanselow
Publisher:
ISBN:
Category : Solid state chemistry
Languages : en
Pages : 554
Book Description
Publisher:
ISBN:
Category : Solid state chemistry
Languages : en
Pages : 554
Book Description