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  • 11
    Electronic Resource
    Electronic Resource
    Will the real FeCO please stand up? (1997)
    Springer
    JBIC 2 (1997), S. 516-520 
    Details
    ISSN: 1432-1327
    Keywords: Key words Myoglobin-CO ; Bond distortion ; Bond energy ; CO poisoning ; Hydrogen bond ; Infrared ; Raman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The paradigm that nature protects us from CO poisoning by forcing the bound CO to bend over in heme proteins, thereby reducing its binding affinity, is now in textbooks, but is nevertheless problematic. Results from vibrational spectroscopy give no evidence for bent CO, although X-ray crystallography continues to indicate appreciable distortions in myoglobin. However, the energetic significance of the discrepancy is doubtful, since new Density Functional Theory calculations indicate that much less energy is required to distort the CO than had been thought, perhaps 2 kcal/mol or less. Binding studies on site-directed mutants of myoglobin suggest that steric hindrance by the distal histidine is worth ca. 1 kcal/mol. While the distal histidine does account for the discrimination by Mb against CO and in favor of O2, most of the effect is due to its H-bond with bound O2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050164
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  • 12
    Electronic Resource
    Electronic Resource
    Note on the density matrix for an arbitrary number of closed shells in a bare Coulomb field (1992)
    Springer
    Journal of mathematical chemistry 9 (1992), S. 291-294 
    Details
    ISSN: 1572-8897
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mathematics
    Notes: Abstract An explicit relation between the density matrix and its s-state part is analyzed for electron closed shells moving in a bare Coulomb potential. The density matrix has a simple separable form in terms ofr 1 +r 2 and |r 1 −r 2|. It is demonstrated that for an arbitrary number of closed shells, the off-diagonal dependence is simply polynomial in the |r 1 −r 2| coordinate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01165153
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    Paper (German National Licenses)
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  • 13
    Electronic Resource
    Electronic Resource
    Effctive nonadiabatic calculations on the ground state of the HD+ molecule (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 55 (1995), S. 245-250 
    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: The nonadiabatic methodology, which is based on an effective elimination of the center-of-mass motion rather than explicit separation achieved by a coordinate transformation, is applied to the ground state of the HD+ molecule. The many-body nonadiabatic wave function is generated in terms of explicitly correlated Gaussian functions. The analytical first and second derivatives of the variational functional with respect to the Gaussian exponents are applied in conjunction with the Newton-Raphson optimization method to find the nonadiabatic energy and the ground-wave function. The numerical results are compared with conventional nonadiabatic calculations. © 1995 John Wiley & Sons, Inc.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560550305
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  • 14
    Electronic Resource
    Electronic Resource
    Matrix elements for Ĵ2 and Ĵz operators over explicitly correlated Cartesian Gaussian functions (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 55 (1995), S. 367-376 
    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: General formalism for evaluation of multiparticle integrals involving J̌2 and J̌z operators over explicitly correlated Cartesian Gaussian functions is presented. The integrals are expressed in terms of the general overlap integrals. An explicitly correlated Cartesian Gaussian function is a product of spherical orbital Gaussian functions, powers of the Cartesian coordinates of the particle, and exponential Gaussian factors, which depend on interparticular distances. This development is relevant to both adiabatic and nonadiabatic calculations of energy and properties of multiparticle systems. © 1995 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560550502
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  • 15
    Electronic Resource
    Electronic Resource
    A graph approach to the gradient expansion of density functionalsAided by a research grant from the Institute of Low Temperatures and Structural Research, Polish Academy of Sciences, Wrocław, Poland. (1986)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 30 (1986), S. 219-226 
    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: A graph representation of terms in the gradient expansion of the kinetic energy density functional is presented. We briefly discuss the implications of the virial theorem for the graph structure and relations between possible graphs at a given order of expansion.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560300721
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  • 16
    Electronic Resource
    Electronic Resource
    Newton-Raphson optimization of the explicitly correlated Gaussian functions for calculations of the ground state of the helium atom (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 54-60 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Explicitly correlated Gaussian functions have been used in variational calculations on the ground state of the helium atom. The major problem of this application, as well as in other applications of the explicitly correlated Gaussian functions to compute electronic energies of atoms and molecules, is the optimization of the nonlinear parameters involved in the variational wave function. An effective Newton-Raphson optimization procedure is proposed based on analytic first and second derivatives of the variational functional with respect to the Gaussian exponents. The algorithm of the method and its computational implementation is described. The application of the method to the helium atom shows that the Newton-Raphson procedure leads to a good convergence of the optimization process. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540150107
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  • 17
    Electronic Resource
    Electronic Resource
    Multicenter and multiparticle integrals for explicitly correlated cartesian gaussian-type functions (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 13 (1992), S. 602-613 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An analytical derivation of multicenter and multiparticle integrals for explicitly correlated Cartesian Gaussian-type cluster functions is demonstrated. The evaluation method is based on the application of raising operators that transform spherical cluster Gaussian functions into Cartesian Gaussian functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540130510
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  • 18
    Electronic Resource
    Electronic Resource
    Application of explicitly correlated Gaussian functions for calculations of the ground state of the beryllium atom (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 566-570 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The electronic energy of atoms and molecules may be evaluated accurately by the use of wave functions where the interelectronic distances are explicitly present. In particular, explicitly correlated Gaussian-type functions make these types of calculations feasible and computationally tractable even for more extended systems. The resulting multielectron integrals may be reduced to standard one- and two-electron integrals that are readily evaluated. Initial calculations have been made for the Be atom where all four electrons were correlated at the same time. The preliminary results show that accurate results may be obtained. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140509
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