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  • 1
    Electronic Resource
    Electronic Resource
    Dynamics with the effective adiabatic theory: The Bloch equations (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 452-458 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper extends our earlier work on the effective adiabatic theory [J. Chem. Phys. 82, 3400 (1985)] to study relaxation of a two-level system coupled to a Gaussian dissipative bath—the spin–boson problem. Bloch equations are derived which, under the limited circumstances described herein, treat the role of bath fluctuations omitted in the equilibrium effective adiabatic reference system. Applications to the Lorentzian dissipative bath show that the theory agrees closely with numerical simulation results. Application to an Ohmic bath shows that the theory is in agreement with currently accepted results concerned with the problem of macroscopic quantum coherence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455488
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The calculation of the thermal rate coefficient by a method combining classical and quantum mechanics (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 2478-2491 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We propose and test a method for computing flux–flux correlation functions (and thermal rate coefficients) which divides the degrees of freedom in two groups, one treated classically and the other quantum mechanically. The method is tested by applying it to a simple model for which we can also obtain exact results. The approximate method gives good results if the mass associated with the classical degrees of freedom exceeds 16 a.u.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454028
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Comments on a model influence functional for quantum systems (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 2861-2862 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We continue the study of a model non-Gaussian influence functional proposed by Allinger, Carmeli, and Chandler [J. Chem. Phys. 84, 1724 (1986)] to approximate the exact influence functional resulting from integrating out all quantum states but those of primary interest. The premise of this work is that the influence of many secondary states on a single primary state can be closely approximated by the influence of a degenerate level of states with equal coupling to the primary state. The degeneracy reflects the fluctuations possible among the secondary states and in fact can be associated with the partition function of the exact secondary states. The new calculations presented herein emphasize the importance of entropic-like effects properly described by this degeneracy, and for the models we examine, our basic premise is shown to be correct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453977
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Non-Gaussian influence functional for quantum systems (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 1724-1731 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We consider the quantum paths (in Euclidean time) through a space of N multiparticle states, and we derive the influence functional for a subset of m primary states in this space. The influence functional results from integrating out the occupation of the N-m nonprimary or bath states holding fixed the time-dependent occupation path through the primary states. The division into bath states and primary states is completely general in principle, though in practice, physical considerations will guide the choice of partitioning. The exact influence functional is nonlocal in time and very complicated in form. We argue, however, by a variational calculation that a simplified approximate functional can be constructed which is very accurate. Unlike the standard Gaussian influence functionals which are inapplicable for processes involving the large amplitude fluctuations of charge transfer and fermionic exchange, the influence functionals described herein are appropriate for models of these processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450470
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  • 5
    Electronic Resource
    Electronic Resource
    Effective adiabatic approximation for a two level system coupled to a bath (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 3400-3404 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We consider the general problem of a two level system coupled to a fluctuating bath. We present a practical and accurate approximate theory for this type of system. Our treatment is based upon a variational perturbation theory in which the reference system is a two level system coupled to an adiabatic fluctuating bath. The methodology is easily generalized to situations involving more than two levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448942
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    Paper (German National Licenses)
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