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  • 1
    Electronic Resource
    Electronic Resource
    Anisotropy of the g -Factor in Aromatic Molecules (1963)
    [s.l.] : Nature Publishing Group
    Nature 198 (1963), S. 283-284 
    Details
    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
    URL: http://dx.doi.org/10.1038/198283b0
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  • 2
    Electronic Resource
    Electronic Resource
    Atomic Units (1959)
    [s.l.] : Nature Publishing Group
    Nature 184 (1959), S. 1559-1560 
    Details
    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
    URL: http://dx.doi.org/10.1038/1841559a0
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  • 3
    Electronic Resource
    Electronic Resource
    Art of citefaction (1987)
    [s.l.] : Nature Publishing Group
    Nature 325 (1987), S. 478-478 
    Details
    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
    URL: http://dx.doi.org/10.1038/325478c0
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  • 4
    Electronic Resource
    Electronic Resource
    Isoelectronic sequences of hydride molecules (1963)
    Springer
    Theoretical chemistry accounts 1 (1963), S. 448-457 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00527094
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  • 5
    Electronic Resource
    Electronic Resource
    The approximation of electron densities (1986)
    Springer
    Theoretical chemistry accounts 69 (1986), S. 63-69 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00526293
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  • 6
    Electronic Resource
    Electronic Resource
    Self-consistent perturbation theory for conjugated molecules (1966)
    Springer
    Theoretical chemistry accounts 6 (1966), S. 159-166 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00526946
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  • 7
    Electronic Resource
    Electronic Resource
    Point charge models for LiH, CH4, and H2O (1973)
    Springer
    Theoretical chemistry accounts 31 (1973), S. 311-324 
    Details
    ISSN: 1432-2234
    Keywords: Point charge models ; One-electron properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Point charge models for LiH. CH4, and H2O are presented. The models preserve the correct total charge and dipole moment of the molecules. Relations between spherical Gaussian wave function values and point charge model values of a variety of one-electron molecular properties are derived. The errors inherent in some of the point charge model values are of two types: those which may be large but are easily evaluated and those which are small and diminish rapidly as the distance from the molecule increases. The models are shown to be a reliable means of calculating one-electron properties and possible uses of the models are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527558
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  • 8
    Electronic Resource
    Electronic Resource
    Book reviews (1980)
    Springer
    Theoretical chemistry accounts 55 (1980), S. 255-256 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556163
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  • 9
    Electronic Resource
    Electronic Resource
    The molecular electrostatic potential of some simple molecules (1986)
    Springer
    Theoretical chemistry accounts 69 (1986), S. 425-436 
    Details
    ISSN: 1432-2234
    Keywords: Molecular electrostatic potential ; Gaussian models ; Point charge models ; Water molecule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The calculation of the molecular electrostatic potential from simplified models of the electron density is considered. Results are shown for water, hydrogen fluoride and ammonia. Little loss of accuracy is evident when the density is represented by a linear sum of well-chosen Gaussians. When these are further simplified into sets of point charges the inner parts of the molecule are poorly represented. More elaborate point moments make the representation worse. On the other hand a mixed representation with point charges and one diffuse Gaussian gives all the essential features of the potential of these molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00526701
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  • 10
    Electronic Resource
    Electronic Resource
    Relativistic effects in aromatic molecules (1966)
    Springer
    Theoretical chemistry accounts 4 (1966), S. 250-259 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Berechnung eines relativistischen Termes, nÄmlich des Bahn-Bahn-Anteiles des Breit'schen Hamilton-Operators, ist bei vorhandenem Magnetfeld in allgemeiner Form durchgeführt worden. Bei konjugierten Molekülen erscheinen im Ausdruck für die zugehörige EnergieÄnderung zwei Arten von Integralen und ihren Ableitungen. Die Wechselwirkung liefert einen intermolekularen Beitrag zur diamagnetischen SuszeptibilitÄt, der allerdings im Fall zweier paralleler Benzolringe um den Faktor α 2 kleiner als die innermolekularen Terme ist. In diesem Zusammenhang traten einige bisher nicht benötigte Integrale auf, deren asymptotische Entwicklung durchgeführt wurde.
    Abstract: Résumé Nous avons étudié, en forme générale, la correction relativiste due a l'opérateur orbite-orbite de Breit en présence d'un champ magnétique. Pour les molécules conjuguées, l'effet énergétique de ce terme peut Être exprimé par deux types d'intégrales et leurs dérivées. La contribution intermoléculaire a la susceptibilité diamagnetique est trouvée, pour deux noyaux parallèles de benzène, d'Être d'un facteur α 2 plus petit que les termes moléculaires. Quelques intégrales moléculaires, incalculées jusque la, ont été évaluées par expansion asymptotique.
    Notes: Abstract Evaluation of the relativistic correction due to the orbit-orbit operator of the Breit Hamiltonian has been considered in general, including the presence of a magnetic field. For conjugated molecules, the change in energy due to this relativistic effect is shown to be expressible in terms of two types of integrals and their derivatives. The interaction results in an intermolecular contribution to the diamagnetic susceptibility which, for two parallel benzene rings, is found to be smaller than the molecular terms by a factor of α 2. Several molecular integrals not previously evaluated were encountered, and their evaluation as asymptotic expansions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00528477
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