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  • 1965-1969  (212)
  • Chemical Engineering  (186)
  • Atomic, Molecular and Optical Physics  (26)
  • Magnetic resonance imaging
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 1 (1967), S. 421-425 
    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 a calculé, pour un déterminant de Slater projeté sur un sous-espace de spin défini, les fonctions de densité pour deux électrons, définies par McWeeny.
    Abstract: Die Zweielektronenfunktionen von McWeeny, sind für eine Spin-projizierte Slaterdeterminante berechnet worden.
    Notes: The two-particle density functions introduced by McWeeny are calculated for a spin-projected Slater determinant.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 13-15 
    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 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 1 (1967), S. 675-692 
    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: Les matrices de densité du premier et du second ordre D(N) et D2(N) pour la fonction g(n) = AN[g(1, 2) … g(N - 1, N)] sont emprimées par la fonction même g(1, 2) et par sa matrice de densité D. Dans l'état singulet les fonctions génératices pour les parties spatiales sont simplement liées à la résolvante de l'équation de Fredholm dans laquelle la partie spatiale D sert de noyau. Quelques cas particuliers de g(1, 2) sont considérés. On établit que le nombre de grandes valeurs propres D2(N) ne dépasse pas le nombre de valeurs propres différentes de D. Ainsi c'est la perturbation dans le spectre D qui produit ces grandes valeurs propres.
    Abstract: Die Dichtematrizen der ersten und zweiten Ordnung D(N) und D2(N) für die Funktion g(n) = AN[g(1, 2) … g(N - 1, N)] werden durch die Funktion g allein und ihre Dichtematgrix erster Ordnung D ausgedrückt. Im Singletzustand hangen die erzeugenden Funktionen für die räumlichen Teile dieser Matrizen mit dem Resolventum von Fredholms Gleichung, mit dem räumlichen Teil von D als Kern zusammen. Hier werden einige spezielle Fälle für g(1, 2) betrachtet. Es wurde festgestellt, dass die Zahl der grossen Eigenwerete D2(N) Die Zahl der verschiedenen Eigenwerte von D nicht übersteigt. Somit hat die Degeneration im Spektrum D das Auftreten von solchen grossen Eigenwerten zur Folge.
    Notes: The first- and second-order density matrices D(N) and D2(N) for the function g(n) = AN[g(1, 2) … g(N - 1, N)] are expressed by the g function itself and its density matrix D. In a singlet state the generating functions for spatial parts of these matrices are simply connected with there solvent of the Fredholm equation in which the spatial part of D is a kernel. Some special cases of g(1, 2) are considered. It isestablished that the number of large eigenvalues of D2(N) does not exceed that of different eigenvalues of D. Thus the degeneracy in the spectrum of D causes the appearance of such large eigenvalues.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 1013-1025 
    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: All-electron SCF-LCAO-MO computations for diazomethane, ketene and allene are presented. The basis functions are contracted Gaussian orbitals. Theoretical results are discussed and related to available experimental data.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 169-184 
    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 discuss the properties of one version of the least squares (LS) method for the solution of the Schrödinger equation. These properties are exemplified by a number of calculations on the n1S and n3S states of helium, up to principal quantum number three, which are very much more accurate than previous LS calculations on helium. Particular attention is paid to the convergence properties of the LS procedure and we compare it with the simpler Rayleigh-Ritz (RR) procedure in the case when the RR matrix elements are evaluated numerically over the same quadrature mesh as used in the LS procedure. We conclude that although the LS procedure is capable of high accuracy it has no advantages which would justify its sole use in place of the RR procedure. However, it does have some advantages when used in conjunction with RR, in that it gives an estimate of the numerical accuracy of the RR energies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 673-673 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 15 (1969), S. 809-814 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental and analytical study was made to determine how well the material functions, derived from the Spriggs four-constant viscoelastic model, could describe the rheological properties of polymer melts. Viscosity and elasticity of selected polymer melts were experimentally determined in the rotational and oscillatory modes using a Weissenberg Rheogoniometer. The Spriggs model was chosen for study because of its success in describing experimental data for polymer solutions and because of its uniqueness in combining results from molecular theory with results from the theories associated with continuum mechanics. It was found that the model provides a good description of the rheological data for polymer melts and that some of the model parameters depend upon the molecular characteristics of the polymer. Since this model contains a small number of well defined constants, it should be useful in developing dimensionless engineering correlations for the complex flows encountered in processes of industrial importance. Deviations between the theoretical and experimental results are discussed and deficiencies of the model noted.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 369-377 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical and kinetics model is presented for reactions catalyzed by solid surfaces where both competitive and noncompetitive adsorption take place, a situation that may be general in reactions between large and small molecules catalyzed by solid surfaces.In the adsorption of large molecules steric hindrance or multiple site adsorption cause maximum surface coverage of such molecules before all sites are occupied. This does not, however, preclude further adsorption of small molecules on the remaining isolated vacant sites nor does it preclude further surface reaction. The overall reaction model for such conditions may be expressed as This particular model has been evaluated for the catalytic hydrogenation of propylene and isobutylene with the expectation that it may be useful in reactions that are of industrial importance. A reaction model based on either competitive adsorption or noncompetitive adsorption alone fails to correlate the experimental data.In these two reactions maximum rates occur at olefin concentrations below 5 mole % and the catalytic adsorption constants for the olefins are a hundredfold greater than for hydrogen. This reaction model is similar to that proposed by Bond and Turkevich (15), who have further demonstrated through the deuteration of propylene that the actual mechanism of the reaction is much more complicated.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 15 (1969), S. 454-459 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The onset of rotational flow instability was determined experimentally for dilute solutions of six polymers. In general, the onset of secondary motions occurred later than for a Newtonian liquid of equal apparent viscosity, although, depending upon geometric ratios, some instabilities occurred earlier than in the Newtonian liquid. The stability theory of Ginn and Denn was used to calculate viscometric normal stress functions for ten solutions, with excellent agreement obtained with rheogoniometric measurements of the primary normal stress measurements in all but three cases. Torque measurements of the laminar secondary motion following instability showed some frictional drags significantly less than those observed in Newtonian liquids, a phenomenon analogous to the turbulent drag reduction observed previously in dilute polymer solutions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The proper forms and asymptotic characteristics of constitutive equations which may be useful for the description of viscoelastic fluids in flow fields of engineering interest are considered. It is seen that the Deborah number emerges as a natural ordering parameter which determines, on the one hand, whether simple approximations explicit in stress may suffice to describe the fluid properties or, on the other hand, whether implicit or integral equations are required. Methods of scale-up are discussed.
    Type of Medium: Electronic Resource
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