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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 6639-6643 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The successive ionization potentials (IP's) of atoms He–Zn are calculated using the relativistic and correlated local-density RCXi method. The contribution of correlation energy to IP's of these atoms are reported. It is found that these correlation contribution to IP's are different for different IP's of the same atom. It is also different for a given IP for different atoms. This behavior is qualitatively explained on the basis of the results of pair-correlation energy. A simple approximate expression to calculate the pair-correlation energy proposed earlier is discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 4009-4014 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have recently proposed a "fully'' correlated relativistic local density method called RCXi method [M. Vijayakumar, N. Vaidehi, and M. S. Gopinathan, Phys. Rev. A 40, 6834 (1989)] for atoms and it has been shown that the results are of near Dirac–Hartree–Fock (DHF) accuracy. In this paper, the extension of the RCXi method to molecules by modifying the standard multiple-scattering Xα (MS-Xα) method is presented. Then, the modified method is applied to calculate various molecular properties such as the molecular correlation energy, the molecular orbital energy levels, the molecular orbital ionization energies, expectation value of 1/r, and magnetic property like isotropic shielding constant for atoms in molecules. Such calculations are made for several molecules including some of them containing heavy atoms. The calculated molecular properties are compared with the available experimental results and with results calculated by other methods. The effects of relativistic and correlation corrections on these molecular properties are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 110 (1988), S. 96-104 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 67 (1985), S. 199-209 
    ISSN: 1432-2234
    Keywords: Electronic energy partitioning ; molecular electronic virial theorem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The partitioning of the molecular electronic energy into true one-electron quantities defined by a molecular electronic virial theorem (MEVT) is studied for a number of molecules. Since the theorem is derived for exact wavefunctions, its applicability to various ab initio wavefunctions at difierent levels of accuracy is examined. The average percentage deviations of the theorem for near Hartree-Fock, double zeta, STO-6G and STO-3G type wave functions are 0.4, 1.7, 2.3 and 3.3, respectively.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 70 (1986), S. 303-322 
    ISSN: 1432-2234
    Keywords: Molecular orbital valency ; Bonding nature ; Mulliken ; Walsh diagrams
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Valency is defined for each molecular orbital. The molecular orbital valency values are shown to be a good measure of the bonding nature of the molecular orbital. Comparisons are made with photoelectron spectral studies and Mulliken overlap population analysis. The variation of molecular valency and molecular orbital valency with bond angle is studied. It is found that for all the molecules presently considered, energy is linearly related to valency and that the molecular valency reaches a maximum at the equilibrium bond angle. It is also shown that the molecular orbital valency can serve as a quantitatively reliable ordinate for Mulliken-Walsh diagrams.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 68 (1985), S. 343-349 
    ISSN: 1432-2234
    Keywords: Valency changes ; Woodward-Hoffmann reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An analysis of valence changes in selected organic gas phase reactions, calculated on SINDO1 potential surfaces, is performed. It is shown that transition states and intermediates have diradical character if singlet and triplets states are nearly degenerate. As a consequence, normal valencies are expected in Woodward-Hoffman allowed reactions and reduced valencies in forbidden reactions. The formalism is also applied to cationic reactions, but the effects of valency changes are less pronounced.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 37 (1990), S. 685-699 
    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: Earlier definitions of valencies of atoms, molecules, and molecular orbitals are extended to configuration interaction (CI) wave functions. Using these definitions, valencies both at equilibrium and nonequilibrium geometries of molecules are calculated at the CI level and compared with non-CI results. CI valency correlation diagrams are obtained. Valency variation with bond length using correlated wave functions is found to behave properly unlike in the case of SCF wave functions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 965-974 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A modified scheme of a previously developed concept of atomic valence numbers in molecules is presented. The relation to population analysis is demonstrated. The scheme is suitable for ab initio wave functions with extended basis sets. The procedure involved a combination of symmetric orthogonalization and contraction of the basis set. The method is used for a systematic investigation of a series of compounds with first-row atoms from Li to F. The predicted atomic charges and valence numbers are in line with results from infrared spectroscopy and multipole moment analysis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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