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  • 1
    Electronic Resource
    Electronic Resource
    Classical trajectory and statistical adiabatic channel study of the dynamics of capture and unimolecular bond fission. V. Valence interactions between two linear rotors (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 9987-9998 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The combination of two linear rotors forming linear or nonlinear adducts is treated using standardized valence potentials. Classical trajectory (CT) and statistical adiabatic channel (SACM) calculations are used for the calculation of thermal capture rate constants. At very low temperatures, only SACM applies. At intermediate temperatures SACM and CT approach each other; however, Landau–Zener-type multiple crossings of adiabatic channel potentials introduce local nonadiabaticity which has to be accounted for. The high-temperature transition from globally adiabatic to nonadiabatic (sudden) dynamics is studied by CT. Thermal rigidity factors, accounting for the influence of the anisotropy of the potential on the capture rate constant, are expressed in simple analytical form which facilitates practical applications. The present work complements similar studies on the addition of atoms to linear molecules in standardized valence potentials (part IV of this series). © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476497
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  • 2
    Electronic Resource
    Electronic Resource
    Classical trajectory and statistical adiabatic channel study of the dynamics of capture and unimolecular bond fission. IV. Valence interactions between atoms and linear rotors (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 5265-5280 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The addition of atoms to linear molecules forming linear or nonlinear adducts is treated using standardized valence potentials. The dynamics is analyzed with a combination of classical trajectory (CT) and statistical adiabatic channel (SACM) calculations. For classical adiabatic conditions, the two approaches coincide. The transition from adiabatic to nonadiabatic dynamics is investigated using CT calculations. The low-temperature adiabatic quantum range is studied by SACM. Thermal capture rate constants are represented in analytical form. Thermal rigidity factors are expressed in terms of molecular parameters such as the frequencies of transitional bending modes, the bond dissociation energy, the rotational constant of the linear fragment, and the ratio of the looseness and Morse parameters α/β of the potential-energy surface. The final rate expressions are of simple form suitable for direct practical applications. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475963
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  • 3
    Electronic Resource
    Electronic Resource
    Double-cone problem revisited: Effect of the geometric phase on the broad semiclassical resonances (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 6748-6755 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a semiclassical analysis of resonance states supported by a conical potential well coupled to a conical peak. The positions of the energy levels are calculated by Wentzel–Kramers–Brillouin (WKB) procedures, which are applied to an adiabatic Hamiltonian with the contribution from the geometric phase taken into account. The probability of escape from the well is calculated by resorting to a comparison equation of the Zener–Dykhne–Chaplik type. The widths of the energy levels are calculated via the escape probability by using a general relation derived recently by Zhu, Nikitin, and Nakamura [J. Chem. Phys. 104, 7059 (1996)]. It is shown that the present calculations are in excellent agreement with accurate numerical data for the positions and widths as recovered from an analysis of the scattering matrix and from a direct calculation of the complex-valued energy levels. The results obtained explain the very fast decay of the low-lying states and the good performance of the surface-hopping approximation. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474918
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  • 4
    Electronic Resource
    Electronic Resource
    Statistical adiabatic channel calculation of accurate low-temperature rate constants for the recombination of OH radicals in their ground rovibronic state (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 2083-2091 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Accurate low-energy capture cross sections and low-temperature capture rate constants for two OH radicals in their ground rovibronic states X 2Π3/2(v=0, j=3/2) were calculated within the statistical adiabatic channel approach. The rate constants calculated in first order provide a good approximation to the true rate constant below 4 K. The rate constants calculated in second order provide a correction of about 25% to the first order rate constant at 20 K and indicate an only weak temperature dependence at T(approximately-greater-than)20 K. At higher temperatures deviation of the potential from long-range electrostatic interaction have to be accounted for. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469683
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  • 5
    Electronic Resource
    Electronic Resource
    Classical trajectory and adiabatic channel study of the transition from adiabatic to sudden capture dynamics. II. Ion–quadrupole capture (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 6270-6276 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Classical trajectory calculations of ion–permanent quadrupole+induced dipole capture processes are performed over wide ranges of conditions. The results are expressed in two-parametric analytical form, and analyzed with respect to the transition from sudden to adiabatic dynamics. The results are compared with the statistical adiabatic channel model (SACM). For this purpose, adiabatic channel potential curves are expressed in approximate analytical form. The agreement between classical trajectory and SACM results is excellent in the range of adiabatic quasiclassical motion of the collision partners. Analytical expressions can well describe the temperature variation of the capture rate constant in the transition range between the quantum and classical limits. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472468
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  • 6
    Electronic Resource
    Electronic Resource
    Classical trajectory and adiabatic channel study of the transition from adiabatic to sudden capture dynamics. I. Ion–dipole capture (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 6263-6269 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Classical trajectory calculations of ion–permanent+induced dipole capture processes are performed over very wide ranges of conditions. The results are represented in a simple, two-parametric analytical form of high precision. The transition from adiabatic to nonadiabatic dynamics is expressed in terms of the Massey parameter. In the adiabatic range, perfect agreement (better than 0.4%) of the derived thermal capture rate constants from classical trajectories and results from accurate statistical adiabatic channel (SACM) calculations is obtained. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472480
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  • 7
    Electronic Resource
    Electronic Resource
    Recovery of the Landau matrix elements from the classical Fourier components: The one-dimensional dissociating oscillator (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2027-2033 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The recently suggested method of recovering the Landau exponent of the quasiclassical matrix elements from the attributes of classical motion is illustrated by way of an example of dissociating anharmonic oscillators. For a Morse oscillator, in which case the exact analytical results are available, the so-called improved semiclassical approximation that incorporates the Landau exponential yields quite accurate matrix elements for classically strongly forbidden events. This provides a firm support for the method of estimation of quasiclassical matrix elements between distant states from the information on the motion of system in the classically allowed region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466554
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  • 8
    Electronic Resource
    Electronic Resource
    Vibrational predissociation rate from dynamics of a full collision: A test of the Landau method against the exact results (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 8065-8071 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We applied the Landau method of calculating the coupling matrix element for a bound–free transition to the evaluation of the vibrational predissociation rate constant of the van der Waals complex ICl*–Ne. Use of the adiabatic separation of the radial and angular motion of the van der Waals modes complemented with the angular averaging with the help of the dominant natural expansion wave function of the bending mode, calculated by Lipkin, Moiseyev, and Leforestier [J. Chem. Phys. 98, 1888 (1993)], yields the rate constant which is about 10%–15% lower compared to the best theoretical estimates. This disagreement is ascribed to the true dynamical interaction between the stretching and bending modes which cannot be incorporated into the adiabatic separation of motion of these modes. Different approximations for treating bending motion are discussed and the sensitivity of the rate constant to the variation of principle parameters of the potential energy surface is studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467262
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  • 9
    Electronic Resource
    Electronic Resource
    Dynamics of charge transfer Ar++(3P)+He(1S)→Ar+(2P)+He+(2S) at low collision energies: Comparison of experimental results with quasiclassical calculations of the differential cross sections (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 807-812 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Differential cross sections of the elementary process Ar++(3P)+He(1S)→Ar+(2P)+He+(2S) at collision energies between 0.6 and 1.6 eV were calculated using the quasiclassical treatment. Analytic potentials providing an approximation of the electronic energy of the system were employed to calculate deflection functions. Coupling of the diabatic terms was evaluated using the asymptotic method, and the Landau–Zener model was applied to account for the transition probability. Semiquantitative agreement of the calculated differential cross sections with those obtained in crossed beam experiments was achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450579
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  • 10
    Electronic Resource
    Electronic Resource
    Rotational relaxation in a free expansion of HCl (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 4423-4428 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational relaxation of HCl in a free jet expansion was studied in a pump-and-probe experiment using infrared laser excitation and resonant multiphoton ionization detection. Rate constants were determined for various J to J' energy transfer processes in the vibrationally excited molecule. There is a strong indication that the rotational energy transfer occurs via a near-resonant dipole–dipole interaction between vibrationally excited and vibrationally cold HCl molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462833
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