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  • 1
    Electronic Resource
    Electronic Resource
    Calculation of oscillator strengths for π-electron molecules (1972)
    Springer
    Theoretical chemistry accounts 26 (1972), S. 87-88 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A comparison of oscillator strengths calculated by the Mulliken and Rieke approximation and by the Hansen expression involving the geometric mean of the dipole-length and dipole-velocity formulae shows that the former method gives values twice as large as those from the latter method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527656
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  • 2
    Electronic Resource
    Electronic Resource
    PPP calculations of the absorption spectra of purines and pyrimidines (1970)
    Springer
    Theoretical chemistry accounts 16 (1970), S. 309-315 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine Variante der PPP-MO-Methode, in der die Zweizentren-Rumpf-Integrale aus dem Gradienten der Überlappungsintegrale berechnet werden und die Parameter nach einer speziellen Methode erhalten werden, wurde benutzt, um die Absorptionsspektren einiger Purine und Pyrimidine, die von biologischem Interesse sind, zu berechnen. Die Übergangsenergien und die Oszillatorstärken geben den Gang und die absoluten Werte der experimentellen Spektren zufriedenstellend wieder.
    Abstract: Résumé Les spectres d'absorption de quelques purines et pyrimidines d'intérêt biologique ont été calculés par une variante de la méthode PPP MO, dans laquelle les intégrales de coeur bicentriques sont calculées à partir du gradient des intégrales de recouvrement et les paramètres sont obtenus par une méthode non arbitraire. Les énergies de transition et les forces d'oscillateur obtenues rendent compte d'une manière satisfaisante des faits expérimentaux.
    Notes: Abstract A variant of the PPP MO method, in which the two-centre core integrals are calculated from the gradient of the overlap integrals and the parameters are obtained by a non-arbitary method, has been used to calculate the absorption spectra of some purines and pyrimidines of biological interest. The transition energies and oscillator strengths obtained account satisfactorily for both the trends and the absolute values of the experimental spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00529432
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Semi-empirical π-electron calculations (1969)
    Springer
    Theoretical chemistry accounts 13 (1969), S. 56-64 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mit einer Methode zur Berechnung der nicht-diagonalen Kernintegrale mit Hilfe des Gradienten der Überlappungsintegrale wird die Parameterisierung der PPP SCF MO-Methode für π-Elektronen-Moleküle studiert. Die für benzolähnliche Heterocyclen erhaltenen Übergangsenergien stimmen befriedigend mit experimentellen Werten aus Absorptionsmessungen überein.
    Abstract: Résumé Etude de la paramétrisation de la méthode PPP SCF MO pour électrons π, en utilisant une méthode de calcul de éléments de coeur non diagonaux fondée sur le gradient des intégrales de recouvrement. Les énergies de transition obtenues pour les hétérocycles benzéniques sont en accord satisfaisant avec l'expérience.
    Notes: Abstract Using a method for calculating the off-diagonal core integrals based on the gradient of the overlap integrals, the parameterization of the PPP SCF MO method for π-electron molecules has been studied. The transition energies obtained for benzene-like heterocycles are in satisfactory agreement with experimental absorption spectra values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527319
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  • 4
    Electronic Resource
    Electronic Resource
    PPP and CNDO calculations for protonated molecules (1970)
    Springer
    Theoretical chemistry accounts 16 (1970), S. 303-308 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung CNDO-Rechnungen wurden benutzt, um die Einzentren-Rumpf-Integrale für protonierte Azine zu erhalten, die bei der Berechnung der π→π * -Absorptionsspektren mit Hilfe der PPP-Methode benötigt werden. Die berechneten Spektren für die Ausgangsmoleküle und die protonierten Moleküle sind in zufriedenstellender Übereinstimmung mit dem Experiment. Die Veränderungen im σ-Rumpf der Moleküle bei der Protonierung werden ebenfalls mit Hilfe der CNDO-Resultate diskutiert.
    Abstract: Résumé Des CNDO ont tét utilisés pour obtenir les intégrales de coeur monocentriques des azines protonées nécessaires au calcul de leur spectre d'absorption π→π * par la méthode PPP. Les spectres calculés pour les molécules protonées ou non sont en accord satisfaisant avec l'expérience. Les modifications subies lors de la protonation par le squelette σ sont discutées en fonction des résultats des calculs CNDO.
    Notes: Abstract CNDO calculations have been used to obtain the one-centre core integrals for protonated azines required in calculating the π→π * absorption spectra of such molecules using the PPP method. Calculated spectra for both the parent and the protonated molecules are obtained in satisfactory agreement with experiment. The changes in the σ-framework of the molecules on protonation are also discussed in terms of the CNDO results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00529431
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    PPP calculations of the circular dichroism spectra of some dinucleoside phosphates (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1091-1102 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichriosm (CD) spectra have been calculated for serveral dinucleoside phosphates using a variant of the Pariser-Parr-Pople π-electron molecular orbital method. This method does not require the prior knowledge of the experimental absorption spectra of transition moments of the bases forming the dinucleoside phosphates. Calculated spectra were obtained in good agreement with experimental spectra for four dinucleoside phosphates, ApA, UpU, GpA, and UpA, and reasonable agreement was obtained for ApG and ApU. The effect of changing conformation on the CD spectrum was studied for ApA, UpU, UpA, and ApU; the spectra of UpU, UpA, and ApU were sensitive to small change in conformation, whereas ApA was insensitive over the range of conformation studied. Further studies await detailed knowledge of the structure of dinucleoside phosphates in solution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1972.360110511
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    Paper (German National Licenses)
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