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  • Atomic, Molecular and Optical Physics  (19)
  • Wiley-Blackwell  (19)
  • International Union of Crystallography
  • Springer
  • 1980-1984  (15)
  • 1965-1969  (4)
Collection
Publisher
  • Wiley-Blackwell  (19)
  • International Union of Crystallography
  • Springer
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 763-774 
    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 Racah method, proposed for the evaluation of coefficients of fractional parentage (CFP) for single shell configurations, is generalized for the cases of two and more than two shells. On the basis of the generalized Racah method, we have evaluated one-particle CFP for all states of svpμ electronic configurations. Two-particle CFP are expressed through one-particle CFP and Racah coefficients.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
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  • 2
    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
    Description / Table of Contents: La méthode des orbitales moléculaires alternantes (AMO) est plus efficace quand les orbitales moléculaires sont choisies d'une maniére optimale. Une méthode est présentée pour la détermination de la combinaison la plus efficace et pour le choix des orbitales moléculaires. Application aux systémes non-alternants (le fulvéne et l'azuléne) montre qu'on peut obtenir une amélioration substantielle dans la valeur de l'énergie par la détermination optimale des MO.
    Abstract: Die Methode der Alternierenden MO(AMO) ist wirksamer, wenn die MO auf optimale Weise gewählt werden. Es wird ein Verfahren für das beste Paarungs-Schema und die Wahl der MO gegeben. Anwendung an nicht-alternierenden Molekülen (Fulven und Azulen) zeigt, dass man eine wesentliche Verbesserung in der Energie erreichen kann, wenn die optimalen MO angewandt werden.
    Notes: The alternant molecular orbital method (AMO) is more efficient if the molecular orbitals are chosen in an optimal way. A method is given of how to determine the most effective pairing scheme and how to choose the starting molecular orbitals. Applications to non-alternant systems (fulvene and azulene) show that one can achieve substantial improvement in the energy by determining the best MO's.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 2 (1968), S. 341-347 
    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
    Description / Table of Contents: On présente une démonstration inductive du théorème de Löwdin concernantl'indépend-ance liréaire d'un set convenablement sélectionné de fonctions propres de spin projetées.
    Abstract: Es wird ein induktiver Beweis für Löwdins Theorem über die lineare Unabhängigkeit und Vollständigkeit eines richtig gewählten Satzes von Spineigenfunktionen gegeben.
    Notes: An inductive proof is given of Löwdin's theorem about the linear independence and completeness of a properly selected set of projected spin eigenfunctions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 47-55 
    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 method of the relativistic investigation of the energy spectra and the electronic transitions in the case of complex configurations, based on the theory of the irreducible tensorial operators and the genealogical coefficients, is described. The use of the quasispin and isospin technique in the relativistic approximation is discussed. Expressions are presented for electric multipole transition probabilities for general values of the gauge condition of electromagnetic field potential.
    Additional Material: 2 Tab.
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  • 5
    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 isospin basis is put into operation for investigation of atomic configurations, having two shells of equivalent electrons, characterized by the same orbital (LS coupling) or total (jj coupling) angular momenta of each electron. Tensorial properties of both the operators and the wave functions are studied in this basis. The two-particle operator is expressed in terms of the tensors irreducible in the isospin space. The problem of the additional classification of the levels is considered. The accuracy of the quantum numbers of the isospin basis in jj coupling scheme is discussed.
    Additional Material: 2 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 267-291 
    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 propose a variant of the coupled-cluster (CC) method in which spin orbitals of the reference Slater determinant are optimized in a self-consistent way. This approach is a reformulation of the Brueckner-Hartree-Fock (BHF) method used in nuclear physics and known also as the exact SCF method. We discuss the use of the reference-state determinants built of HF, natural, and Brueckner spin orbitals, with relations among them investigated in terms of the many-body perturbation theory (MBPT). It is shown that the Brueckner spin orbitals emerge as a convenient basis set in the coupled-cluster method and equations that determine these spin orbitals are found. The Brueckner spin orbitals can be calculated as eigenvectors of a certain Hermitian one-electron operator which has a form of the Hartree-Fock operator plus a “correlation potential” depending linearly on two- and three- electron cluster amplitudes. The usual decoupling scheme in the coupled-cluster method leads to a hierarchy of approximations; in the first nontrivial one the three-electron cluster amplitudes are neglected, and the two-electron ones are determined by solving Čižek's CPMET equations. We also analyze the problem of spatial, spin, and time-reversal symmertry in the CC and BHF methods. If (and only if) the reference-state determinant belongs to a one-dimensional representation of a certain symmetry subgroup of the system, the CC operator and the BHF one-electron operator are invariant with respect to this subgroup. Thus the restricted (entirely symmetry-adapted) version of the BHF method can be formulated only for the closed-shell systems. This is done for the above-mentioned approximate BHF method. We discuss also the usefulness of the BHF method in application to extended metallic systems.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 1001-1012 
    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 mirror reflection symmetry which consists in the correlation of the substitution j → -j -1 with the reflection of the coordinate system and of m → -m with the reflection of the space with respect to the xy-plane has been applied to the quasi-spin formalism. The phases of the wave functions of the shell of equivalent atomic electrons treated as partially filled, as they relate to those when the same shell is treated as almost filled, have been established. The mirror reflection symmetry has been generalized for the supplementary quantum numbers used for distinguishing the terms of the same kind. The phases of the coefficients of fractional parentage of almost filled shell enabling us to determine them from those of partially filled shell have been specified. Corresponding phase relations for the matrix elements of operators have also been considered.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1221-1227 
    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
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1483-1484 
    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
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 585-591 
    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 procedure has been developed for automatic optimization of molecular structures in the EHT method with possible inclusion of electrostatic correction terms, operating with analytical formulas for the first derivative of the total energy in Cartesian coordinates in the s, p, d basis of Slater orbitals. Illustrative examples are given of optimization of the structural parameters of FeCl3, Fe2Cl6, FeCl4, FeCl4-, FeCl2, and FeCl2+ and of optimization of the reaction pathways of the dissociation of Fe2Cl6 yielding the other species of the above set. The values are in good argreement with the available experimental data; this agreement is discussed briefly in connection with the general applicability of the EHT method combined with automatic geometry optimization to theoretical study of compounds containing transition metal atoms.
    Additional Material: 1 Tab.
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