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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 5565-5573 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper, we present a method for the calculation of dispersion interaction energies of molecules, which is based on the localized molecular orbitals of the supermolecule. It is shown (using various basis sets) that the energy contributions of the localized molecular orbitals, for distances around the intermolecular energy minimum, are transferable to a fairly good approximation from the noninteracting monomers to the supermolecule. The correlation energy component of the interaction energy can be separated into inter- and intraparts. We show how the basis set superposition errors can be located and separated at the correlated level. Results are presented for several systems [(H2O)2, (NH3)2, and Ne2 ] with different basis sets from the minimal one to the split shell plus polarization functions. The method applies the well-known Boys' localization procedure and has the advantage that for the dispersion energy at a given geometry, the integral transformation should only be carried out once (from the basis functions to the localized molecular orbitals of the supermolecule).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 115 (1993), S. 6901-6903 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 42 (1976), S. 261-271 
    ISSN: 1432-2234
    Keywords: Method of moments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Some precautions needed in the choice of weight functions when calculating wave functions by the method of moments are analysed. It appears that an important criterion for “good” weight functions is that the difference between the “total” and the “truncated” overlaps (both defined in the paper) be high. The method of moments is applied to wave functions involving Hylleraas-type correlation factors using weight functions made up of products of single-particle orbitals. The aim of the calculations is partly to test the criteria for “good” weight functions, partly a preparation of more extended calculations of a similar type.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 45 (1977), S. 111-120 
    ISSN: 1432-2234
    Keywords: Localized molecular orbitals, density distribution and spatial models of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The widely-employed “principal lobe” description of localized molecular orbitals is evaluated. Spatial decompositions of bond and lone pair LMO densities for a series of ten-electron hydrides are presented. “Tail” populations are ≃ 10 % of the total. The 0.001 electron a.u.−3 contour of the principal lobe contains ≃ 90 % of the pair population. A recent statistically defined cone model of valence orbital distribution correctly locates the central 45–50 % of the density. An earlier ellipsoidal model volume encompasses a much smaller fraction of the population, in agreement with its predictions on “ideal” Gaussian distributions.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 50 (1978), S. 31-38 
    ISSN: 1432-2234
    Keywords: Localized molecular orbitals, basis dependence of ∼, moments of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effects of Gaussian basis set contraction and addition of polarization functions on H2O localized orbitals have been studied at the experimental geometry. It is shown that the electric moments and moment features of localized orbitals are not influenced very much by basis set quality variations, as going from medium size to enlarged basis sets. The difference between bond pair and lone pair charge densities was found to be larger on approaching the Hartree-Fock limit. A minimal basis set, however, does not suitably characterize the localized charge distributions.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 53 (1979), S. 147-157 
    ISSN: 1432-2234
    Keywords: Localized MOs, transferability of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The localized molecular orbitals of some related ten- and eighteen-electron systems have been studied. The transferability of the kinetic, self-interaction, Coulomb and exchange interaction energies on localized orbitals have been shown. The standard deviation of the kinetic and of the interaction energies (including exchange) are less than 2.5% except for lone pair orbitals of the oxygen atoms where the standard deviation is close to 4%.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 43 (1976), S. 161-164 
    ISSN: 1432-2234
    Keywords: Method of moments ; Unrestricted spin-projected HF equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Basic principles of a possibility of simplifying the unrestricted spin-projected Hartree-Fock equations by means of the method of moments are outlined.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2234
    Keywords: Proton affinities of CH2O and CH2OH+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Vertical proton affinities were calculated with closed and open shell direct SCF-MO methods for the ground, excited triplet and ionized doublet states of CH2O and CH2OH+. The computed gas phase basicity of CH2O follows the order: CH2O(1 A 1) 〉 CH2O*(3 A 1 or 3 A 2) 〉 CH2O+(2 B 2 or 2 B 1).
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 56 (1980), S. 259-267 
    ISSN: 1432-2234
    Keywords: Localized MO's, Transferability of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The transferability of the first and second order electric moments of localized orbitals have been shown. Some moment characteristics have also been investigated. The standard deviation of first order localized moments is less than 2.0%. The standard deviation of second order electric moment components are larger: although they do not exceed 4.0% for bond orbitals, for lone pair ones they vary about 1.5–10.1%.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-2234
    Keywords: Correlation energy ; Many-body perturbation theory ; Localized orbitals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The second-order energy corrections are calculated for some normal saturated hydrocarbons by using the many body-perturbation theory (MBPT) based on localized orbitals. The correlation energies are expressed as the sum of contributions from virtual orbital pairs. We have found that these contributions are transferable and have interesting structural features: the trans-coplanar effects are relatively large. Partitioning the correlation energies according to the “order of neighbourhood” we have found that the zero order effects are the largest but the first and second neighbour contributions are also important.
    Type of Medium: Electronic Resource
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