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  • 1
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Paargleichungen 1. Ordnung wurden für die Reihe der Ionen mit 4 Elektronen von Li− bis Ne6+ gelöst. Ein Variations-Störungsverfahren wird mit numerischen Methoden verknüpft, um eine Methode zur Berechnung von Paarfunktionen zu erhalten, die genau ist und möglichst geringe Rechenzeiten benötigt. Die Variation der Paarkorrelationsenergien als Funktion der Atomnummer wird diskutiert und das asymptotische Verhalten vonE 2(l) wiel −4 undl −6 für Singulet- und Tripletzustände wird bestätigt. Für Lithium wird die Elektronenaffinität abgeschätzt.
    Abstract: Résumé Résolution des équations de paires au premier ordre pour la série à 4 électrons: Li− à Ne6+. Un procédé de perturbation variationnel est lié à des méthodes numériques pour engendrer une méthode de calcul des fonctions de paires simultanément précise et économique. La variation des énergies de corrélation de paires en fonction du nombre atomique est discutée ainsi que le comportement asymptotique deE 2(l) par rapport àl −4 etl −6 pour les états singlet et triplet respectivement.
    Notes: Abstract The first order pair equations have been solved for the four electron sequence Li− to Ne6+. A variational perturbation procedure is blended with numerical methods to generate a method for computing pair functions which is both accurate and efficient with respect to time of computation. The variation in the pair correlation energies as a function of atomic number is discussed and the asymptotic behaviour ofE 2(l) asl −4 andl −6 for singlet and triplet states respectively is corroborated. An estimate is made for the electron affinity of lithium.
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  • 2
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Einige dimere Modelle, die Züge der Loch- und Polaronenvorstellungen vereinigen, werden für das hydratisierte und ammonisierte Elektron vorgeschlagen. Mit Hilfe der erweiterten Hückel-Theorie wird die Grö\e der Löcher in Wasser und Ammoniak bestimmt. Dabei zeigt sich, da\ die Ladung im Wasser fast gleichmÄ\ig über das System verteilt ist, wÄhrend im Ammoniak das Elektron innerhalb des Loches bleibt.
    Abstract: Résumé On propose des modèles de dimères pour l'électron hydraté et ammoniaqué. Ces modèles combinent les caractéristiques des formulations de cavité et de polaron. A l'aide d'un calcul Hückel étendu, on fixe la taille des cavités dans l'eau et l'ammoniaque. L'analyse de population montre que dans l'ammoniaque l'électron reste dans la cavité, tandis que dans l'eau la charge s'étend presque uniformément sur le système.
    Notes: Abstract Some dimer models are proposed for the hydrated and ammoniated electron. These combine features of both the cavity and polaron formulations. By way of an extended Hückel calculation the size of the cavities in water and ammonia is ascertained. A population analysis shows that whereas in water the charge spreads out almost uniformly over the system, in ammonia the electron remains within the cavity.
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
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  • 4
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The muon-electron β-hyperfine coupling constant is reported for the 2-muoxyprop-2-yl radical formed by positive muon (μ+) implantation in propan-2-one and aqueous solutions of propan-2-one. Using the technique of muon spin rotation (μSR) spectroscopy the coupling constant was measured over a full temperature range in which the samples were in the liquid state. In all cases, the coupling constants were found to be small, and to show a positive temperature dependence. In the aqueous mixtures the presence of the water produces a slight lowering, at all temperatures, in the coupling constant with respect to the coupling in pure propan-2-one. An interpretation is given which relates the radical structure, to the barrier hindering internal rotation and to solvent interactions.
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  • 5
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The [PF6]− salt of E-tetraethyl-l,4-diaminobut-2-ene has been synthesized and the crystal structure determined. The experimental electronic charge distribution has been obtained by fitting a multipole model to low-temperature, high-resolution, single-crystal X-ray diffraction data. A high-level ab initio molecular orbital calculation has also been performed for the cation, which is used as an antifungal agent. Both experimental and theoretical Laplacian distributions display maxima only at the bond critical points. This correlates with a calculated electrostatic potential which is positive at all points.
    Type of Medium: Electronic Resource
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