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  • 1
    Electronic Resource
    Electronic Resource
    Accurate three-dimensional quantum scattering studies of long-lived resonances for the reaction He+H+2→HeH++H (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 8085-8097 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The adiabatically adjusting principal-axis hyperspherical (APH) formulation of Pack and Parker for quantum reactive scattering in three dimensions (3D) is used to obtain converged results for the reaction of helium with H+2 (v=1–4) for total angular momentum J=0. The ab initio potential energy surface computed by McLaughlin and Thompson and fitted by Joseph and Sathyamurthy is utilized for the HeH+2 interaction potential. The predicted energy dependence of the accurate 3D state-to-state reaction probabilities show clear evidence for quantum resonances. These resonances are even more numerous than those reported earlier for reduced dimensionality studies of this reaction. The calculated time delays for several of these resonances are found to be over 1 ps. Bending corrected rotating linear model (BCRLM) studies of this same reaction are also reported. These results provide useful insight in sorting out the nature and contribution of the resonances found in the 3D studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459339
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  • 2
    Electronic Resource
    Electronic Resource
    Quantum reactive scattering in three dimensions using hyperspherical (APH) coordinates. IV. Discrete variable representation (DVR) basis functions and the analysis of accurate results for F+H2 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2344-2361 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Accurate 3D coupled channel calculations for total angular momentum J=0 for the reaction F+H2→HF+H using a realistic potential energy surface are analyzed. The reactive scattering is formulated using the hyperspherical (APH) coordinates of Pack and Parker. The adiabatic basis functions are generated quite efficiently using the discrete variable representation method. Reaction probabilities for relative collision energies of up to 17.4 kcal/mol are presented. To aid in the interpretation of the resonances and quantum structure observed in the calculated reaction probabilities, we analyze the phases of the S matrix transition elements, Argand diagrams, time delays and eigenlifetimes of the collision lifetime matrix. Collinear (1D) and reduced dimensional 3D bending corrected rotating linear model (BCRLM) calculations are presented and compared with the accurate 3D calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457976
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  • 3
    Electronic Resource
    Electronic Resource
    Direct calculation of collisional properties that require energy derivatives of the S matrix: Results for the reaction He+H+2(r harp over l)HeH++H (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 2516-2522 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Darakjian–Hayes direct method for determining quantum lifetimes for three atoms scattering in three physical dimensions is used to determine accurate state-to-state time delays for the reaction of helium with H+2 for total angular momentum J=0. These results are compared with the time delays obtained by numerical differentiation of the S-matrix elements generated using the APH (adiabatically adjusting principal-axis hyperspherical) formulation of Pack and Parker. The direct method was found to be accurate and efficient for calculating the energy derivatives of the S matrix. The calculated eigenvalues of Smith's collision lifetime matrix (eigen lifetimes) for this reaction predict numerous long-lived metastable states, many with lifetimes over 0.5 ps. The extent of the coupling of metastable states to specific scattering states provides an indication of the nature and magnitude of the time delays associated with particular state-to-state scattering processes. The direct method for calculating the energy derivatives of the S matrix is also found to be accurate and efficient for determining the energy derivative of the cumulative reaction probability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460956
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  • 4
    Electronic Resource
    Electronic Resource
    Erratum: Direct calculation of collisional properties that require energy derivatives of the S matrix: Results for the reaction He+H+2=HeH++H [J. Chem. Phys. 95, 2516 (1991)] (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 9203-9203 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468508
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of transition state theory with quantum scattering theory for the reaction Li+HF→LiF+H (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 4917-4924 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The validity of transition state theory is examined for the bimolecular reaction of Li+HF→LiF+H. Accurate three-dimensional quantum scattering theory calculations of the cumulative reaction probability are reported for energies ranging from threshold (0.255 eV) up to 0.600 eV and a total angular momentum J of 0. Transition state theory estimates of the effect of both the entrance and exit channels on the cumulative reaction probability are reported for the same energy range and J value. The transition state theory results are found to provide an accurate description of the smoothed energy dependence of the cumulative reaction probabilities with a maximum disagreement between the two calculations of about 25% arising at the highest energy considered of 0.6 eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467211
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  • 6
    Electronic Resource
    Electronic Resource
    Quantum molecular dynamics simulations of liquid alkalies (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7048-7057 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We employ a unified molecular dynamics (MD), quantum mechanical approach to simulate the behavior of large collections of atoms at finite temperature. The nuclei are moved according to classical mechanics while the forces are computed via quantum mechanical models. Two approaches have been used: (1) the extended Hückel method, which is an approximate molecular orbital approach and (2) density functional theory based on the local density approximation and plane wave pseudopotential formulation. We compute properties from the MD trajectories of up to 4 ps duration for samples containing up to 250 atoms of lithium, sodium, and potassium. These results are compared to both previous calculations and experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468330
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  • 7
    Electronic Resource
    Electronic Resource
    An interatomic potential for reactive ion etching of Si by Cl ions (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 5983-5988 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An interatomic potential has been developed to describe the dynamics of Si/Cl systems, with particular relevance to reactive ion etching of Si by energetic Cl ions. We have modified the Stillinger–Weber (SW) potential of Feil et al. by adding two new terms: (1) an embedding term that corrects for the variation in Si–Cl bond strength as a function of the number of neighbors, and (2) a four-body term to describe the variation of the Si–Si bond strength as a function of the number of neighbors of each Si atom and the atom types (a bond order correction). Calculated Si etch rates obtained from molecular dynamics simulations using the new potential are in better agreement with recent experimental results than those obtained with the unmodified potential. Predictions of the stoichiometry of the etch products are also markedly different between the two potentials. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478499
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  • 8
    Electronic Resource
    Electronic Resource
    Quantum reactive scattering in three dimensions using hyperspherical (APH) coordinates. 5. Comparison between two accurate potential energy surfaces for hydrogen atom + hydrogen and deuterium atom + hydrogen (1990)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 8055-8058 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100384a016
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  • 9
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of reactive ion etching of Si by energetic Cl ions (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 3552-3559 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report results from molecular dynamics simulations of the etching of a Si surface by energetic Cl atoms (15 eV≤E≤200 eV). We find that the energy dependence of the Si yield (number of Si atoms desorbed per incident Cl ion) is in reasonable agreement with recent experiments and with previous simulations performed up to 50 eV. We also investigate the variation of the Si yield with the impact angle of incidence, the stoichiometry of the desorbed material, and the effect of a thermal background Cl flux to the surface in the presence of an ion flux at 50 eV. Surface roughening due to etching was observed and the calculated rms roughness is in reasonable agreement with experiments. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365674
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  • 10
    Electronic Resource
    Electronic Resource
    Assignment of peaks in photodetachment spectra using predicted densities of reactive states: Application to H2F− and D2F− (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 4881-4889 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Accurate cumulative reaction probabilities and densities of reactive states have been obtained for the reactions F+H2→H+HF and F+D2→D+DF using the hyperspherical (APH) coordinate scattering method developed by Pack and Parker. Results for scattering energies ranging from threshold to 0.7 eV above threshold have been obtained using two different potential energy surfaces that have been proposed for this system. The predicted peaks in the densities of reactive states are due to the presence of scattering resonances. The characteristic steps in the cumulative reaction probabilities are used to identify the resonance peaks due to quantized dynamical bottlenecks. The trapped-state or Feshbach-type resonances are identified by narrow oscillations in the density of reactive states. The positions of these resonance peaks in the density of reactive states are in good agreement with the peaks in the Franck–Condon factors for the photodetachment of H2F− and D2F−. Significant changes in resonance types are found for the T5a and 5SEC potential energy surfaces for H2F. While the assignment of resonance peaks presented is in reasonable agreement with the assignments suggested by Hahn and Taylor based on their classical mechanical analysis, there are some differences that will require further study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463842
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