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  • 11
    Electronic Resource
    Electronic Resource
    The evaluation of moments for polycyclic hydrocarbons (1986)
    Springer
    Theoretical chemistry accounts 70 (1986), S. 323-332 
    Details
    ISSN: 1432-2234
    Keywords: graph theory ; Graphical invariants ; Moments ; Hüackel theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The evaluation of some moments of the energy in the Hückel theory of conjugated molecules is considered. It is shown that, for molecules consisting entirely of hexagons, the moments μ 4 and μ 6 can be expressed in terms of four graphical invariants. Partial results are given for other molecules. Since the total energy can be expressed as a series of moments the implications for the energy are discussed. In this discussion two other invariants play a major role. The conclusion is suggested that an analysis of moments in terms of graphical invariants should be of prime importance in understanding these molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00540026
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  • 12
    Electronic Resource
    Electronic Resource
    Intramolecular energy transfer in water (1988)
    Springer
    Theoretical chemistry accounts 74 (1988), S. 23-38 
    Details
    ISSN: 1432-2234
    Keywords: Dephasing ; Quantum beats ; Intramolecular energy transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The evolution of the vibrational motion of a water molecule which has been excited locally is studied. An exact solution is obtained of a model Hamiltonian representing the non-harmonic behaviour of the molecule. Since this is obtained numerically it does not explain what is observed but it leads to a simplified model of the motion in which different aspects can be isolated and discussed. For many initial modes, especially those of higher energy, there is a large initial drop in the probability of finding the energy in the original local mode. This is due to dephasing. The factors involved in dephasing are discussed. A simple hypothesis is suggested which leads to a formula for this drop and this agrees substantially with the graphical evidence. The relation between the drop and the amplitude of the initial mode is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570550
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  • 13
    Electronic Resource
    Electronic Resource
    Eigenvalue distributions in alternant hydrocarbons (1993)
    Springer
    Journal of mathematical chemistry 13 (1993), S. 191-203 
    Details
    ISSN: 1572-8897
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mathematics
    Notes: Abstract A theorem due to Lord Rayleigh is applied to the graphs and bual graphs of conjugated hydrocarbon molecules to show how the distribution of their eigenvalues can be understood. A lower bound to the number of eigenvalues larger than or equal to 2 can be predicted easily from the graphs. The uses of the theorem as applied to polyenes, non-alternants and polyhex are illustrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01165564
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  • 14
    Electronic Resource
    Electronic Resource
    Orthogonal trajectories of the electron density (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 12 (1977), S. 623-637 
    Details
    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: Functions of several variables, such as the electron density and the nuclear Born-Oppenheimer potential, may be analysed very effectively using orthogonal trajectories. In particular the behaviour of these trajectories at critical points of the functions is investigated in detail. The use of orthogonal trajectories in the virial partitioning of Bader and in the definition of reaction coordinates is extended. A chemical interpretation of the critical points is suggested. The relevance of catastrophe theory is illustrated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560120404
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  • 15
    Electronic Resource
    Electronic Resource
    What can quantum chemistry contribute to biology? (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 16 (1979), S. 51-56 
    Details
    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: The transition from quantum chemistry to quantum biology is discussed, and the contributions that quantum biology can make to the study of biological structure and process are outlined. The need for extensions to the theory to deal with larger systems, to include solvent effects and to account for specificity, are emphasized.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560160108
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  • 16
    Electronic Resource
    Electronic Resource
    C. A. Coulson and the surface energy of metals: A further comment (1988)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 34 (1988), S. 301-304 
    Details
    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: The role of the boundary conditions is emphasized in determining the relation between the counting problem, posed by Coulson and solved by the number theorists, and the physical problem from which it arises. The surface energy term, which Coulson sought, does exist, but only when the periodic boundary conditions, which he used, are replaced by the finite box conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560340311
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  • 17
    Electronic Resource
    Electronic Resource
    The change in the dressed potential of a polyatomic molecule in intense photon fields: Simple rules based on the nuclear charge-mass ratio (1989)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 35 (1989), S. 283-295 
    Details
    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: An explicit expression for the dressed potential of a polyatomic molecule, in the adiabatic approximation, is derived. This expression clearly shows the importance of the nuclear charge-mass ratio (NCMR) for the change of potential due to photon fields. It is found from a simple calculation that the 1H atom is the only atom having an abnormal NCMR value; all other atoms have similar, or the same, values. This means that only those molecules containing a 1H atom should be strongly affected by fields. On the basis of this new physical insight, we postulate two rules, which enable us to classify molecules, with respect to their response to intense photon fields, into three classes: high-sensitive, low-sensitive, and insensitive molecules. Qualitative verification is also given by using water isotopes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560350205
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  • 18
    Electronic Resource
    Electronic Resource
    Aromaticity measured by Kekulé structures (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 605-613 
    Details
    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: The total energies, in the Hückel theory, of a large number of polyhex molecules and some containing a four-membered ring have been calculated and analyzed. The results confirm that within a set of isomers the number of Kekulé structures is the dominant variable. It is proposed that this term should be recognized as the aromatic term. The remaining contributions to the energy can be attributed to local features of the molecule. Comparison with the Hess-Schaad analysis of the same energies indicates that this treatment is simpler, more complete, and closer to the original concept of aromaticity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560390407
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  • 19
    Electronic Resource
    Electronic Resource
    Integral representation of a fundamental functional for the study of the zero-point vibrational energy of hydrocarbons and the total Pi-electron energy of alternant hydrocarbons (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 41 (1992), S. 613-635 
    Details
    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: A further step is made in investigating the zero-point vibrational energies En (or the total pielectron energies En for the case of alternant hydrocarbons) of lineraly extended system B—An—B′ having n repeating identical moieties. By an approach using the aspects of form and general topology, an integral representation αint of a fundamental functional α, where α(ϕ) = limn→∞ (En(ϕ)/n), has been established, which enables one to treat these energies quantitatively in a unified manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560410407
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  • 20
    Electronic Resource
    Electronic Resource
    Some solutions in the graph theory of alternant benzenoids (1993)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 45 (1993), S. 167-176 
    Details
    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: A new formulation of the eigenvector equations for certain polymeric molecules is given. The electronic bands for the infinite molecules are deduced. For the finite molecules, the use of ghost molecules allows an exact specialization of the infinite to the finite eigenvector equations. The complete solution of the equations depends on the solution of a simple transcendental equation. Approximate solutions of this equation are given that bracket the accurate solutions so that, for molecules with many repeated moieties, the approximations become good. The general theory is illustrated by applications to the chrysene series and to the polyphenyls. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560450204
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