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  • 1990-1994  (5)
  • 1991  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Hardnesses from electrostatic potentials (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 6055-6056 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: By generalization of a method due to Politzer et al. [J. Chem. Phys. 79, 3859 (1983)], it is demonstrated how the absolute hardness of an electronic system can be determined from the electrostatic potential, as a function of position of the system and its positive and negative ions. It is shown that to good accuracy the hardness is one-half the electrostatic potential at the covalent radius due to the Fukui function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460443
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Higher-order derivatives in density-functional theory, especially the hardness derivative ∂η/∂N (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 5559-5564 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Several third derivatives of the ground-state electronic energy E with respect to the electron number N and/or the external potential v, as defined in density-functional theory, are studied. These include the first derivatives of the hardness η. Legendre transforms of η[N,v] are constructed and corresponding Maxwell relations derived. Various new functions and relations are found. The derivative of the hardness with respect to the electron number at constant potential γ is studied numerically for atoms and positive ions, and suggested values are displayed and discussed. Recommended values of γ are positive for most spherical atoms, negative otherwise. Power series expansions of E(N) are not recommended for reasons given. Simple analytical representations are recommended instead.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460491
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    HSAB principle (1991)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 113 (1991), S. 1855-1856 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00005a073
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Principle of maximum hardness (1991)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 113 (1991), S. 1854-1855 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00005a072
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Approximate density matrices and Husimi functions using the maximum entropy formulation with constraints (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 823-837 
    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 entropy of an electronic system is defined in terms of the Husimi function, a nonnegative distribution function in phase space. The Husimi function is calculated by maximizing the entropy subject to the constraints that the Husimi function give a Gaussian convolution of the desity when integrating over the momentum coordinates and that its second moment with respect to momentum give a sum of Gaussian convolutions of the density and the kinetic energy density. The result is compared with the Wigner function. Equations are given for calculating the density matrix from the Husimi function. The resulting equation for the exchange energy requires a difficult numerical integration. An alternate method is used to obtain the density matrix from an approximate partially collapsed Husimi matrix that gives the maximum entropy Husimi function as its diagonal. The results are exact for the harmonic oscillator ground state. Exchange energies calculated for H and the He isoelectronic series through C+4 show slight improvements over those calculated using a maximum entropy Wigner function.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560390607
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    Paper (German National Licenses)
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