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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 34 (1993), S. 2713-2717 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: A fast and absolute converging sequence, for the Thomas–Fermi (TF) initial slope, was obtained by applying a perturbative approach [C. M. Bender et al., J. Math. Phys. 30, 1447 (1989)] to the TF equation written in terms of the electronic density. By this procedure the truncated series does not alternate, in contrast to a previous work [B. J. Laurenzi, J. Math Phys. 31, 2535 (1990)] based in the traditional TF equation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 8548-8556 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Fluctuation formulas for the external potential v(r) are introduced in a modified Legendre-transformed representation of the density functional theory of electronic structure (isomorphic ensemble). A new (nuclear/geometric) reactivity index h(r), having the same status as the electronic Fukui function in the canonical ensemble, is thereby identified, h(r)=(1/N)[δμ/δσ(r)]N,T=(1/kT) [〈μ⋅v(r)〉−〈μ〉〈v(r)〉], where μ is the electronic chemical potential, σ is the shape factor of the electron density distribution, N is the number of electrons, 〈...〉 denotes the ensemble average of a quantity, and 〈v(r)〉 is the ensemble averaged external potential. This new local quantity is shown to be an inverse of the local softness, and to provide a useful definition of a local hardness. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 7645-7646 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 7188-7192 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The exchange energy density functional of an N electron atom is approximated by a combination of the Dirac and the Fermi–Amaldi approximations. The unknown coefficients of the combination are estimated by requiring that the sum of the Coulombic and exchange energies vanish when evaluated with the exact one-electron density. Evaluating the present functional with the Hartree–Fock densities of 1785 atoms and ions, and comparing the resulting exchange energies with the corresponding Hartree–Fock values gave an average error of 2%. The functional derivative has the correct long-range behavior, and leads to an Euler–Lagrange equation whose solutions gave energies which were in very good agreement with the Hartree–Fock values.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 9557-9560 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A previously derived [J. Chem. Phys. 103, 7645 (1995)] general variational principle, for determining the hardness (or band gap) of electronic systems, is applied to π-electron systems by a straightforward simple parameterization of the hardness kernel. For conjugated polyenes and annulenes, the hardness (band gaps) are essentially the same as (although no identical with) those predicted by the Hückel method. In contrast with the Hückel method, one need not assume that the total electronic energy is a sum of one-electron energies. Comparisons are made with Nalewajski's Charge Sensitivity Analysis. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 10621-10626 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Fukui function for a neutral atom is expressed as its LDA approximation plus a one-parameter gradient correction, and the resultant formula is numerically tested. Expressing hardness as a density functional involving this Fukui function, global hardness values are determined for several atoms. Estimates also are made of the covalent radii of neutral atoms. Calculated Fukui functions exhibit characteristics similar to those reported in the literature. Calculated hardnesses compare favorably with experimental values, and predicted covalent radii are in agreement with existing theoretical values and experimental data. No information other than the electron densities of the neutral species enter in the calculations. An exact nuclear cusp condition on the Fukui function is derived. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 29 (1986), S. 937-948 
    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 concept of an atom in a molecule in the context of density functional theory is used to analyze different levels of approximation to the description of interatomic interactions. Such an approach strongly suggests the use of Kohn-Sham atomic densities as an alternative to Hartree-Fock atomic densities in the electron gas model of Gordon and Kim. The results for rare gases and ionic crystals show that both densities lead to similar results.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 231-240 
    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 ground-state energy of an electronic system is a functional of the number of electrons (N) and the external potential (v): E = E[N, v], this is the energy representation for ground states. In 1982, Nalewajski defined the Legendre transforms of this representation, taking advantage of the strict concavity of E with respect to their variables (concave respect v and convex respect N), and he also constructed a scheme for the reduction of derivatives of his representations. Unfortunately, N and the electronic density (ρ) were the independent variables of one of these representations, but ρ depends explicitly on N. In this work, this problem is avoided using the energy per particle (∊) as the basic variable. In this case ∊ is a strict concave functional respect to both of his variables, and the Legendre transformations can be defined. A procedure for the reduction of derivatives is generated for the new four representations and, in contrast to the Nalewajski's procedure, it only includes derivatives of the four representations. Finally, the reduction of derivatives is used to test some relationships between the hardness and softness kernels. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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