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  • 1
    Electronic Resource
    Electronic Resource
    Quadratically convergent calculation of localized molecular orbitals (1982)
    Springer
    Theoretical chemistry accounts 62 (1982), S. 107-132 
    Details
    ISSN: 1432-2234
    Keywords: Localized orbitals ; Molecular orbitals ; Quadratic convergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two iterative procedures for the transformation of canonical self-consistent field molecular orbitals to intrinsic localized molecular orbitals are proposed. A first-order method based on a series of (n × n) unitary transformations may be applied to orbitals which are far from convergence. The second method, based on Newton's method, yields quadratic convergence. Numerical results based on Boys' criterion are presented for water, carbon monoxide, boron fluoride, nitric oxide, and methylacetylene. A composite method may be used to obtain rapid convergence for large molecules for which it is not practical to calculate the entire hessian matrix. The performance of the composite method is demonstrated by application to the dinitrogen tetroxide molecule. Highly converged localized molecular orbitals may be obtained for most molecules with five to eight first-order iterations followed by three or four iterations based on either the second-order or composite method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581477
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  • 2
    Electronic Resource
    Electronic Resource
    Localized orbitals and the Fermi hole (1982)
    Springer
    Theoretical chemistry accounts 61 (1982), S. 265-281 
    Details
    ISSN: 1432-2234
    Keywords: Localized orbitals ; Fermi hole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relationship between localized orbitals and the Fermi hole is demonstrated with contour maps of the Fermi hole in the water molecule. These contour maps indicate the presence of regions in which the Fermi hole is relatively stable, regions in which the shape of the Fermi hole changes rapidly, and regions in which the Fermi hole follows the probe electron smoothly. If a single orbital dominates any region of space, the Fermi hole resembles that orbital for any position of the probe electron in the dominated region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00550971
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Localized orbitals based on the fermi hole (1984)
    Springer
    Theoretical chemistry accounts 66 (1984), S. 279-293 
    Details
    ISSN: 1432-2234
    Keywords: Molecular orbitals ; localized orbitals ; Fermi hole ; density matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Fermi hole provides a direct (non-iterative) method for tansforming canonical SCF molecular orbitals into localized orbitals. Except for simple overlap integrals required to maintain orthogonality, this method requires no integrals over orbitals or basis functions. This method is demonstrated by application to a furanone (C4H4O2), methylacetylene, and boron trifluoride. The results of these calculations are compared to those determined by the orbital centroid criterion of localization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00554785
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Binding of an electron to a molecular dipole: BeF2- (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 741-746 
    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: Results of extended-basis SCF calculations indicate that BeF2- may exist as a metastable species. Comparison of results obtained from SCF calculations on neutral BeF2 with those of BeF2- shows that the orbital occupied by the electron of BeF2- is well approximated by the lowest unoccupied molecular orbital of neutral BeF2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140606
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of the second-order reduced density matrix for correlated electronic wave functions (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 22 (1982), S. 889-902 
    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: Formulas are presented for the evaluation of the second-order reduced density matrix for correlated wave functions, including wave functions constructed from pairwise nonorthogonal orbitals. Numerical results are provided for the correlation holes and conditional nuclear spin densities for the water molecule.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560220504
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  • 6
    Electronic Resource
    Electronic Resource
    Calculation of localized molecular orbitals (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 355-365 
    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: Two techniques are presented for reducing the effort required to determine localized orbitals based on the energy or density criteria. The first, population weighted editing of the electronic repulsion integrals, reduces the effort required for each iteration of the localization procedure. The second, damping/extrapolation of the transformation matrix, reduces the number of iterations required to reach convergence. Numerical results are provided for methane and formaldehyde (for the editing method) and for carbon monoxide and boron fluoride (for the damping/extrapolation technique).
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250208
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    Paper (German National Licenses)
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