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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 6722-6731 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report energy calculations of selected first-row atoms using explicit approximate Hartree-Fock functionals generated in the context of the local-scaling version of density functional theory. We show that these approximate functionals yield highly accurate upper bounds to the Hartree-Fock energies of the atoms considered. The generation of molecular functionals in terms of local-scaling transformations centered at each nucleus is discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 503-512 
    ISSN: 0020-7608
    Keywords: density functional theory ; local-scaling transformations ; kinetic-energy functionals ; exchange-energy functionals ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using several types of simple generating orbitals, explicit expressions for the kinetic-energy functional Ts[ρ] and the exchange functional Ex[ρ] were generated in the context of the local-scaling transformation version of density functional theory. The variational parameters in these orbitals were optimized by a minimization of either the kinetic-energy functional (Kohn-Sham procedure) or the total-energy functional (Hartree-Fock procedure) corresponding to a single Slater determinant. The results obtained for several atoms show that the present kinetic-energy functionals yield values whose percent error is at least an order of magnitude smaller than that of the best available functionals.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 503-512, 1998
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 591-600 
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new model for the exchange potential in the framework of DFT is proposed. The potential is defined as 2αx∊xappr, where ∊xappr is the exchange-energy density and αx is not a constant but a functional αx[ρ] to be determined iteratively. The exact Fock expression and the LDA, GEA, and Becke88 approximations were used as ∊xappr. We provide results for atoms showing that this model potential yields total and exchange energies and other atomic properties that are in good agreement with Hartree-Fock values. In addition, total energies obtained by adding to the αx[ρ] approach correlation energy corrections computed via the WL and LYP functionals are in close accord with experimental values.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 591-600, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 439-450 
    ISSN: 0020-7608
    Keywords: local scaling transformation ; electron correlation ; DFT ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We discuss in the present work the treatment of electron correlation within the context of the local scaling transformation version of density functional theory. This is done by resorting to a locally scaled transcorrelated Hamiltonian of Boys and Handy [S. F. Boys and N. C. Handy, Proc. Roy. Soc. A310, 43 (1969)] which describes electron correlation effects as arising from the action of effective two- and three-particle terms on a single Slater determinant. The expectation value of the locally scaled correlated wave function is expressed in terms of the factor Aviles-Hartog-Tolhoek (FAHT) cluster expansion, and the explicit form of the correlation functional is given up to second order. In particular, an explicit analytic functional is obtained for the effective two-body term. This functional contains ρ5/3, ρ4/3, and ρ2/3 as universal factors. Numerical calculations using the locally scaled correlation wave function are performed for two-electron atoms for which various types of orbitals and correlation factors are tested. The numerical results for the correlation energy of these two-electron systems attest as to the adequacy of the present locally scaled-generated functionals.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 439-450, 1998
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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