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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 35-47 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The full third order (Σ3), quasi-particle third order (Σq3) and Outer Valence Green's Function decouplings of the bi-orthogonal dilated electron propagator have been implemented for the first time and results from their application to 2P Be−, 2P Mg− shape and 2S Be+ (1s−1) Auger resonances are presented and compared with energies and widths obtained using the zeroth order (Σ0), quasi-particle second order (Σq2) and second order (Σ2) decouplings. The energies and widths from third order decoupling for shape resonances are close to those obtained using second order self-energy approximants. The energy and width calculated using the third order decoupling for Auger resonances provide better agreement with experimental results, with the much more economic quasi-particle third order decoupling being just as effective. The differences between FDAs from different decouplings are analyzed to elicit the role of correlation and relaxation in the formation and decay of shape and Auger resonances. © 2001 American Institute of Physics.
    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 115 (2001), S. 4549-4557 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The full third order (Σ3), quasi-particle third order (Σq3) and outer valence Green's function (OVGF-A) decouplings of the bi-orthogonal dilated electron propagator have been implemented and results from their application to 2Π CO−, 2Πg N2−, and 2Πg C2H2− shape resonances are presented and compared with energies and widths obtained using the zeroth order (Σ0), quasiparticle second order (Σq2) and second order (Σ2) decouplings. The energies and widths from the various Σ3 decouplings for shape resonances are close to those obtained using the Σ2 approximant but the corresponding Feynman–Dyson amplitudes (FDAs) differ considerably. The differences between FDAs from different decouplings are analyzed to elicit the role of correlation and relaxation in the formation and decay of shape resonances. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 2336-2342 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An examination of the dependence of total flux from competing photodissociation channels on the photolysis field parameters and initial vibrational states for IBr and HI molecules reveals that, for a range of field attributes, considerable selectivity and yield may be obtained by using only the ground or the ground and the first excited vibrational states in the optimal linear combination constituting the field optimized initial state (FOIST). The new simplifications obviate the need for overtone excitations or multicolor photolysis fields making it easier to implement FOIST experimentally. Concrete specifications of field attributes for achieving selective control of IBr photodissociation products is provided. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 25 (1989), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : An hydraulic description of moisture transport through the compacted clay layers of a landfill cover liner is presented. Previous descriptions have assumed that micro-pore processes control the transport. The present description incorporates the influence of voids or macro-pores created by desiccation cracking. The existence and importance of cracks is documented using laboratory and field data. Although micro-pore flow can be modeled confidently using Darcy's Law, the contribution of macro-pore flow is often neglected because of the lack of field verified models to describe its occurrence. The variety of modes and mechanisms of flow that are operative in flow through cracked clay liners is discussed, and analogies are made to familiar concepts in open channel flow theory. The discussion provides the conceptual framework for the development of a numerical model to simulate both the micro- and macro-pore flow phenomena.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 25 (1989), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The existence and importance of macro-pores to the containment efficiency of cover clay liners at waste landfills is documented. Macro-pores exist as voids, or cracks, and act to increase the volume and rate of leakage through cover liners. Existing numerical models used to simulate flow through clay liners are shown to neglect the macro-pore aspect of the problem. Current theories of macro-pore flow developed from related areas of research are presented, and applications to the landfill liner problem are considered.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 676-682 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The zeroth (Σ0), second order (Σ2), quasiparticle second order (Σ2q), diagonal two-particle one-hole Tamm Dancoff approximation (Σ2ph-TDA) and the quasiparticle diagonal 2ph-TDA (Σq2ph-TDA) decouplings have been applied to investigate the 2Π CO− and 2B2g C2H4− shape resonances. An examination of the resonant roots and the corresponding Feynman Dyson amplitudes (FDAs) reveals that the most economic and effective description is offered by the second order decoupling. The more demanding diagonal two-particle one-hole Tamm Dancoff approximation (2ph-TDA) is shown to be less effective and the quasiparticle decouplings are shown to be no better than the zeroth order (bivariational self-consistent field) approximation in the description of molecular shape resonances. The correlation and relaxation effects incorporated by the Σ2 and Σ2ph-TDA decouplings are shown to assist resonance formation by lowering the antibonding nature of the lowest unoccupied molecular orbitals (LUMOs) on the real line and by turning these into anionic diffuse orbitals suitable for metastable electron attachment for the optimal value of the complex scaling parameter. The use of complex resonance energies calculated here to construct a nonempirical optical potential for the investigation of vibrational dynamics of these resonances is suggested. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 2023-2032 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A general iterative inversion algorithm based on first-order functional sensitivity analysis and Tikhonov regularization is extended for the determination of diabatic coupling potentials from inelastic scattering data. For simplicity, the two-state case is presented here, and it is assumed that the (diagonal) diabatic potentials are known. "Noisy'' and "noise-free'' numerically simulated data, calculated from model potentials for He++Ne and Li+I, are used to illustrate the method. Various coupling potential trial functions are used, ranging from a constant multiple of the model to a step function. For most cases, the important regions of the coupling potential (i.e., those regions which are most sensitive to the inelastic scattering data, including the region of crossing) are recovered to high precision within four to seven iterations. Those cases which show a small range for convergence may indicate a limit of the present algorithm, based solely on first-order functional derivatives, and the need to extend it to include higher-order terms.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2044-2051 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The orbital picture of shape resonances is investigated by examining the radial charge density distributions calculated from resonant Feynman–Dyson amplitudes for the 2P shape resonances in e-Be, e-Mg, and e-Ca scattering using the zeroth (bivariational self-consistent field), second order and the diagonal two particle one hole-Tamm–Dancoff approximation decouplings of the dilated electron propagator. A comparison between the radial density distributions from the highest occupied and the resonant orbital/Feynman–Dyson amplitude(s) reveals an accumulation of the electron density near the target for optimal value of the complex scaling parameter. The nodal pattern of the radial distributions differs from that expected for the lowest unoccupied p orbitals but their dominant contribution to the charge density distribution is clearly seen. A study of the difference between the radial densities obtained from various decoupling schemes highlights the role of correlation and relaxation in the characterization of these resonances. The role of coordinate space span of the primitive Gaussian-type orbital basis in characterization of these resonances is discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 112-117 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 95 (1991), S. 3109-3118 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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