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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 184 (1959), S. 1559-1560 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The use of such more conventional energy units as kcal./mol., eV., or cm.-1, for example, avoids some of the confusion concerning multiplicity of unit, but has other decided disadvantages. These units are not the primary result of the calculation and the conversion factors depend on the currently ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 325 (1987), S. 478-478 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR-In a recent leading article (Nature 324, 95; 1986) you mention the possibility of citation counts being used to measure the research effectiveness of a university. Citations counts are important for other purposes and will appear to politicians to be a natural choice for this purpose, so they ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 198 (1963), S. 283-284 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The feasibility of observing ring-current effects in electron spin resonance experiments has been investigated by calculating the #-factor anisotropy for a number of molecules. The origin of the effect lies in the spin-other-orbit terms of the full molecular Hamiltonian. Their magnitude has been ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 5 (1966), S. 148-158 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zesummenfassung Im Rahmen des SCF-LCAO-Verfahrens wird eine Einteilchen-Störung behandelt and ein numerisches Verfahren zur Berechnung der Änderung der Matrix der Bindungsordnung angegeben. In der vorliegenden Arbeit wird diese Methode benützt, um Atom-Atom-Polarisier-barkeiten und Spindichten für eine Anzahl von Kohlenwasserstoffen zu berechnen sowie ihre chemische Reaktivität zu diskutieren.
    Abstract: Resume La théorie des perturbations monoélectroniques est developpée au contexte du procédé LCAO autocohérent de fonctions d'ondes moléculaires. On décrit une méthode numérique pour le calcul de changements dans la matrice de charge et d'ordre de liaison dûs aux perturbations monoélectroniques. Suivant cette méthode sont calculées les polarisabilités atome-atome autocohérentes pour un nombre d'hydrocarbures conjugués. A l'aide des résultats on calcule des densités de spin, et discute la réactivités chimiques.
    Notes: Abstract The theory of one-electron perturbations is developed in the context of the self-consistent LCAO treatment of molecular wavefunctions. A numerical method of calculating changes in the charge and bond order matrix due to one-electron perturbations is described. The method is used to compute self-consistent atom-atom polarizabilities for a number of conjugated hydrocarbons. The results are applied to spin-density calculations and to a discussion of chemical reactivity.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 69 (1986), S. 63-69 
    ISSN: 1432-2234
    Keywords: Electron density ; Gaussian 80 ; Point charge models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper discusses the approximate representation of the electron density produced by an ab initio calculation. A linear combination of Gaussians is fitted to the density by minimizing a functional which is the consequent error in field-energy. The practical implementation of the procedure, following a Gaussian 80 calculation, is described and some of the complications are analysed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 69 (1986), S. 71-81 
    ISSN: 1432-2234
    Keywords: Electron density ; Gaussian models ; Point charge models ; Water molecule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electron density of the water molecule, as calculated by a standard program, is approximated by linear combinations of spherical Gaussians. The accuracy of the result is studied as a function of the numbers and positions of the Gaussians. Since this shows where the charge is located in the molecule it has immediate physical significance. The building-up of the density can be followed in more and more detail. From these expansions, point charge models of water are readily deduced. These are compared with models of similar kinds used by other authors. Some of the calculations have been repeated with a wavefunction of higher accuracy to investigate the stability of the results. Results show that the more accurate density requires more Gaussians to represent its greater complexity.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 6 (1966), S. 159-166 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ein äußeres elektrisches Feld verschiebt die π-Elektronen in der Molekülebene, so daß die elektrische Polarisierbarkeit von Molekülen mit konjugierten Bindungen anisotrop ist. Mittels SCF-Störungsrechnung wurde der Beitrag der π-Elektronen zum Tensor der Polarisierbarkeit für eine Anzahl von Molekülen berechnet und der Beitrag des σ-Bindungsgerüstes aus semiempirischen Größen ermittelt. Die Übereinstimmung mit gemessenen Werten ist zufriedenstellend.
    Abstract: Résumé La polarisabilité électrique des molécules conjuguées est anisotrope car un champ extérieur provoque un déplacement des électrons π mobiles dans le plan moléculaire. La théorie des perturbations SCF est utilisée pour le calcul de la contribution des électrons π au tenseur de polarisabilité d'un certain nombre de molécules conjuguées. En utilisant des valeurs théoriques et semi-empiriques antérieures concernant les polarisabilités des liaisons C-C et C-H on peut évaluer la contribution des électrons σ. Les polarisabilités totales sont obtenues comme la somme des contributions σ et π. L'accord avec les données expérimentales disponibles est raisonnable.
    Notes: Abstract Since an external field produces a drift of the mobile π-electrons in the plane of a conjugated molecule the electric polarizability of these molecules is anisotropic. The S.C.F. perturbation theory is used to calculate the π-electron contribution to the polarizability tensor for a number of conjugated molecules. Using previous theoretical and semi-empirical values for the polarizabilities of C-C and C-H bonds the σ contribution is estimated and total polarizabilities for the molecules obtained as the sum of the σ and π contributions. There is reasonable agreement between these theoretical values and the available experimental ones.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 1 (1963), S. 448-457 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Theorie der Elektronenstruktur zweiatomiger Hydride wird untersucht, wobei die zweite Kernladungszahl frei veränderbar bleibt. Durch Einführung eines Maßstabfaktors, der sowohl von Kernladungszahl als auch zwischenatomarem Abstand abhängt, läßt sich die Schrödingergleichung in eine die Durchführung einer Störungsrechnung möglich machende Form bringen. Die Energien nullter und erster Näherung werden für eine Anzahl isoelektrischer Reihen berechnet, allein der Vergleich mit dem Experiment zeigt, daß Terme höherer Ordnung in die Rechnung mit einbezogen werden müssen, um Grundeigenschaften der Moleküle deuten zu können.
    Abstract: Résumé La théorie de la structure électronique des hydrures diatomiques est étudiée, où la charge nucléaire du second noyau est variable. A l'aide d'un facteur d'échelle dépendant de la charge nucléaire et de la distance internucléaire l'équation de Schrödinger peut être mise dans une forme convenable à un calcul perturbateur. Les énergies de nullième et de premier ordre sont calculées pour quelques séquences isoélectroniques; mais la comparaison de l'expérience montre qu'il faut des termes de plus grand ordre pour expliquer les propriétés fondamentales des molécules.
    Notes: Abstract The theory of the electronic structure of diatomic hydrides in which the nuclear charge of the second nucleus is varied freely is investigated. By the use of a scale factor which varies with both the nuclear charge and the internuclear distance, the electronic equation can be put into a form suitable for a perturbation expansion. The zero and first order energies are computed for á number of isoelectronic sequences but comparisons with experiment show that higher order terms are needed in order to explain the basic properties of the molecules.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 55 (1980), S. 255-256 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 74 (1988), S. 75-82 
    ISSN: 1432-2234
    Keywords: Cavity models ; muon ; μSR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The form of various cavity models are discussed with regard to their prediction of the isotropic hyperfine coupling constants of the “normal muonium” states in group IV elements. Neither the bulk dielectric constant nor the cavity radius seem to be as important as the detailed variation of the dielectric function very close to the trapped nucleus.
    Type of Medium: Electronic Resource
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