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  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Optimization procedure for the cooling of liquid 3He by adiabatic demagnetization of praseodymium nickel (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 437-443 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction and performance of a single stage nuclear demagnetization apparatus utilizing 0.267 mole of praseodymium nickel material is described. An optimization procedure to minimize entropy production during the demagnetization of the hyperfine enhanced material has been developed which enabled the cryostat to cool a liquid-3He sample to a temperature of 350 μK. The effects of measured heat leaks and inferred eddy-current heating are accounted for satisfactorily in a model of this procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138319
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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
    A detailed three-dimensional quantum study of the Li+FH reaction (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 1238-1250 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Accurate quantum reactive scattering calculations in the full three-dimensional physical space have been carried out for the Li+FH reaction at zero total angular momentum using the adiabatically adjusting principal axis of inertia hyperspherical coordinate formalism. The procedures for fitting the potential energy surface, calculating the surface functions, and propagating the solutions in a coupled channel treatment are given and discussed. Features of the resulting reactive probability plots are analyzed, and simple explanations of a number of the quantum resonance and oscillatory features are found. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468911
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    The role of carbon on the electrical properties of polycrystalline Si1−yCy and Si0.82−yGe0.18Cy films (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 6182-6189 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A comparison is made of the electrical effects of carbon in n- and p-type in situ doped polycrystalline Si1−yCy and Si0.82−yGe0.18Cy layers. Values of resistivity as a function of temperature, effective carrier concentration and Hall mobility are reported. The n-type polycrystalline Si1−yCy and Si0.82−yGe0.18Cy films show dramatic increases in resistivity with carbon content, rising from 0.044 Ω cm to 450 Ω cm (0 and 0.8% C) and 0.01 Ω cm to 2.4 Ω cm (0 and 0.6% C), respectively. In contrast, the increase in B-doped films is much less severe, rising from 0.001 Ω cm to 0.939 Ω cm (0 and 7.9% C) and 0.003 Ω cm to 0.015 Ω cm (0 and 4% C) for the Si1−yCy and Si0.82−yGe0.18Cy layers, respectively. The grain boundary energy barrier, determined from the temperature dependence of the resistivity, is found to vary as the square of the C content in the n-type polycrystalline Si1−yCy and Si0.82−yGe0.18Cy layers, but linearly in the p-type Si1−yCy layers. The square law dependence seen in the n-type layers for C contents up to 0.9% is explained by an increase in the grain boundary trap density due to the presence of carbon, whereas the linear relationship seen in the p-type layers for C contents between 2% and 8% is explained by a shift in the grain boundary trap energy toward the valence band. Finally, lower values of grain boundary energy barrier are obtained in p-type Si0.82−yGe0.18Cy layers with a C content of 4% than in equivalent Si1−yCy layers, which could be explained by a larger shift in trap energy toward the valence band. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1343896
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  • 8
    Electronic Resource
    Electronic Resource
    Plasma chemistry at long mean-free-paths (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1940-1945 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A long mean-free-path (lmfp) model of transport of neutral particles has been developed and applied to the chemistry of a low neutral-pressure ((approximately-less-than)2 mTorr) plasma etching system. In cylindrical geometry, using coordinates (r,z) while ignoring angle φ, a transition matrix is set up for an arbitrary mfp that indicates the fraction of the particles originating in the cell at (r',z') that experience their next collision in the cell at (r,z). This matrix can be iterated, allowing for chemical reactions, to obtain the steady state density of the neutral species. It can also provide angular distributions of neutrals; at present, their energy distribution is not kept track of, although it will be in the future. The method has been applied to an electron cyclotron resonance plasma in CF4. Using the measured electron energy distribution, the breakdown of CF4 into the species responsible for etching is calculated. Densities of CF4, CF3, CF2, and F are presented for a wide range of conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356341
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  • 9
    Electronic Resource
    Electronic Resource
    Phase diagram for a model exchange-disordered magnetic alloy: Physical principles (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5976-5978 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The mean-field phase diagram for an XY model on a square lattice is studied. At low temperatures, noncollinearity can be produced by individual "strong'' impurity bonds or a finite concentration of "weak'' impurity bonds. Thermal fluctuations tend to destroy this noncollinearity, leading to a collinear state at low enough impurity concentrations. For both "weak'' and "strong'' impurities the phase diagram has a multicritical point like that found by Gabay and Toulouse. However, "very strong'' impurity bonds lead to noncollinearity at all temperatures where there is magnetic order, and yield a phase diagram with a multicritical point unlike that of Gabay and Toulouse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346033
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  • 10
    Electronic Resource
    Electronic Resource
    Li+FH reactive cross sections from J=0 accurate quantum reactivity (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2269-2270 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Accurate three dimensional quantum calculations have been carried out for the Li+HF reaction at zero total angular momentum J on a potential energy surface fitted to ab initio points. By adopting a J shifting approximation reactive cross sections are estimated and compared with the experiment. The agreement is very good.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465238
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