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  • 1
    Electronic Resource
    Electronic Resource
    Alternative definition of exchange-correlation charge in density functional theory (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 6197-6203 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new definition of the exchange-correlation charge is presented. This charge is related to the exchange-correlation potential of density functional theory by the Poisson equation. It is illustrated how, using the Zhao–Morrison–Parr method, this new exchange-correlation charge can be evaluated numerically, thus providing direct input for the ongoing process of finding improved approximate density functionals. Several properties of this new charge, including the sum rule and Coulombic-like behavior, are derived. Both atomic shell and subshell structures are observed. Exchange-correlation charges generated from various approximate functionals are calculated and compared with numerically accurate data for a few atoms. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479924
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Chemical potential, hardness, hardness and softness kernel and local hardness in the isomorphic ensemble of density functional theory (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 3000-3006 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: New relations among reactivity descriptors are provided within the recently introduced modified isomorphic ensemble of density functional theory. In addition, expressions for the softness and hardness kernel are derived in the canonical, grand canonical, isomorphic, and grand isomorphic ensemble. There results a new definition for the local hardness, η(r)=[∂u(r)/∂N]σ=ησ−g(r), where g(r)=[∂υ(r)/∂N]σ and σ=ρ/N is the shape factor. This identifies the local hardness as a function measuring the response of the system's external potential to a perturbation in electron number at a constant shape factor. Furthermore, it is shown that one cannot represent both local softness and local hardness unambiguously with one representation. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474657
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  • 3
    Electronic Resource
    Electronic Resource
    Second-order density-functional description of molecules and chemical changes (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 5578-5586 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Based on functional expansion methods recently developed, the total energy of an atomic and molecular system is expanded in terms of its chemical potential (electronegativity), hardness, softness, Fukui function, response function, and so on, up to the second order. Expansions are given within the four basic ensembles in density functional theory: the canonical, grand canonical, isomorphic, and grand isomorphic ensembles. The formulas obtained provide explicit relations among the important quantities related to the chemical reactivity of a system, and they provide a means to calculate one quantity when others are known. Furthermore, a favorable viewpoint of the maximum hardness principle follows from these formulas. At fixed electron number, external potential and chemical potential, the global hardness should go to a maximum as the total energy approaches a minimum. Arguments for the second-order truncation are given. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473580
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  • 4
    Electronic Resource
    Electronic Resource
    Exchange - correlation potential and excited-state density functional theory (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 535-543 
    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 exchange-correlation potential associated with excited-state density functional theory is studied numerically using accurate electron densities for ground and excited states of He, Be, Ne, Mg, and Ar. The long-range and short-range behaviors of this potential are discussed. First-excitation energies are estimated using various prescriptions. © 1996 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Polynomial and Padé Representations for the Kinetic Component Tc[ρ] of the Correlation Energy Density Functional (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 513-522 
    Details
    ISSN: 0020-7608
    Keywords: density functional theory ; correlation energy ; kinetic energy ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polynomial and Padé representations of the kinetic energy component Tc[ρ] of the correlation energy density functional Ec[ρ] are presented in this article. Two approximate local formulas similar to the Wigner form for Ec[ρ] are investigated for Tc[ρ]. Applications of these formulas along with their two polynomial counterparts are carried out for atoms, ions, and a few simple molecules. Numerical predictions of Tc values are made for these species. Both Hartree-Fock and self-consistent-field densities are used in their evaluations. Recommended at this time is the two-parameter Padé [0, 1] formula Tc[ρ]=∫a0ρ/(1+b0ρ-1/3) dr, with a0=0.1658 and b0=6.102 (atomic units).   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 513-522, 1998
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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