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Recursive generation of natural orbitals in a truncated orbital space

Authors

  • Xiangzhu Li,

    Corresponding author
    1. Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
    • Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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  • Josef Paldus

    1. Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
    2. Department of Chemistry, Guelph–Waterloo Center for Graduate Work in Chemistry, Waterloo Campus, University of Waterloo, Ontario N2L 3G1, Canada
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Abstract

We describe a procedure that generates a subset of low-lying natural orbitals. It employs a small truncated orbital space, whose dimension is essentially given by the number of natural orbitals we wish to generate. The method is somewhat related to the numerical renormalization group technique. The resulting low-lying, optimal natural orbitals can then be used in the computation of one-electron properties, as well as of the energy via a small-scale configuration interaction (CI), yielding improved potential energy and property surfaces over those obtained with the same method using Hartree–Fock orbitals. The procedure is illustrated on a DZP model of water, considering both the dipole moment and the total energy at the equilibrium and symmetrically stretched geometries. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

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