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  • Articles: DFG German National Licenses  (3)
  • exchange effects  (2)
  • 1,3-Butadiene  (1)
  • 1
    Electronic Resource
    Electronic Resource
    A new quantum statistical evaluation method for time correlation functions (1989)
    Springer
    Journal of statistical physics 54 (1989), S. 765-795 
    Details
    ISSN: 1572-9613
    Keywords: Time correlation functions ; Liouville operators ; cluster expansion ; exchange effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Considering a system ofN identical interacting particles, which obey Fermi-Dirac or Bose-Einstein statistics, we derive new formulas for correlation functions of the type $$C(t) = \langle \Sigma _{i = 1}^N A_i (t) \Sigma _{j = 1}^N B_j \rangle $$ (whereB j is diagonal in the free-particle states) in the thermodynamic limit. Thereby we apply and extend a superoperator formalism, recently developed for the derivation of long-time tails in semiclassical systems. As an illustrative application, the Boltzmann equation value of the time-integrated correlation functionC(t) is derived in a straightforward manner. Due to exchange effects, the obtained t-matrix and the resulting scattering cross section, which occurs in the Boltzmann collision operator, are now functionals of the Fermi-Dirac or Bose-Einstein distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01019775
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Quantum-statistical kinetic equations (1989)
    Springer
    Journal of statistical physics 56 (1989), S. 175-201 
    Details
    ISSN: 1572-9613
    Keywords: Kinetic equations ; exchange effects ; renormalized cluster series ; quantum-statistical Boltzmann and Choh-Uhlenbeck equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Considering a homogeneous normal quantum fluid consisting of identical interacting fermions or bosons, we derive an exact quantum-statistical generalized kinetic equation with a collision operator given as explicit cluster series where exchange effects are included through renormalized Liouville operators. This new result is obtained by applying a recently developed superoperator formalism (Liouville operators, cluster expansions, symmetrized projectors,P q rule, etc.) to nonequilibrium systems described by a density operatorρ(t) which obeys the von Neumann equation. By means of this formalism a factorization theorem is proven (being essential for obtaining closed equations), and partial resummations (leading to renormalized quantities) are performed. As an illustrative application, the quantum-statistical versions (including exchange effects due to Fermi-Dirac or Bose-Einstein statistics) of the homogeneous Boltzmann (binary collisions) and Choh-Uhlenbeck (triple collisions) equations are derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01044240
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of substituting phosphorus for a ring carbon atom in the valence isomers cyclobutene, bicyclobutane, and 1,3-butadiene. a quantum-chemical investigation (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 419-425 
    Details
    ISSN: 0009-2940
    Keywords: Cyclobutene ; Bicyclobutane ; 1,3-Butadiene ; Phosphorus substitution ; Relative energies ; Quantum chemical investigations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclobutene, bicyclobutane, and 1,3-butadiene are valence isomers within the concept of the Woodward-Hoffman rules. According to thermochemical considerations and in agreement with energy optimized quantum-chemical calculations at the ab initio RHF and MP2/6-31G(d,p) levels bicyclobutane is the least and 1,3-butadiene the most stable valence isomer. Phosphorus substitution exerts a considerable effect on the relative stabilities of the various valence isomers. Bicyclobutanes containing phosphorus atoms in the bridgehead positions are considerably more stable than the other phosphorus-substituted valence isomers. This conclusion was confirmed by an analysis of the natural bond populations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290410
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    Paper (German National Licenses)
    Fulltext
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