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  • 1
    Electronic Resource
    Electronic Resource
    A variational approach to nonlocal exciton–phonon coupling (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2728-2740 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we apply variational energy band theory to a form of the Holstein Hamiltonian in which the influence of lattice vibrations (optical phonons) on both local site energies (local coupling) and transfers of electronic excitations between neighboring sites (nonlocal coupling) is taken into account. A flexible spanning set of orthonormal eigenfunctions of the joint exciton–phonon crystal momentum is used to arrive at a variational estimate (bound) of the ground state energy for every value of the joint crystal momentum, yielding a variational estimate of the lowest polaron energy band across the entire Brillouin zone, as well as the complete set of polaron Bloch functions associated with this band. The variation is implemented numerically, avoiding restrictive assumptions that have limited the scope of previous assaults on the same and similar problems. Polaron energy bands and the structure of the associated Bloch states are studied at general points in the three-dimensional parameter space of the model Hamiltonian (electronic tunneling, local coupling, nonlocal coupling), though our principal emphasis lies in the understudied area of nonlocal coupling and its interplay with electronic tunneling; a phase diagram summarizing the latter is presented. The common notion of a "self-trapping transition'' is addressed and generalized. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473793
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  • 2
    Electronic Resource
    Electronic Resource
    Micromagnetic modeling of magnetic anisotropy in textured thin-film media (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6411-6415 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Existing micromagnetic models, based on single domain grains that individually follow coherent rotation during reversal, have been utilized to study the effect of various texture-induced microstructures on the hysteretic behavior of Co-alloy thin films with circumferentially textured substrates. The roles of preferential orientation of Co c axes, grain elongation, and segregation, as well as possible short-range intergranular coupling, have been examined in an effort to understand the origins of widely observed magnetic anisotropy in these media. Preferential c-axis distribution along the track direction yields reasonable remanences and coercivities for both circumferential and radial loops, but the observed loop closure remains unaccounted for by c-axis distribution alone. Closely packed arrays of elongated grains maintain relative isotropy in terms of magnetostatic interactions, while voids along texture lines contribute to the magnetostatic anisotropy of the film. The limitations of the model are also discussed. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359114
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  • 3
    Electronic Resource
    Electronic Resource
    Reduced density matrix and combined dynamics of electrons and nuclei (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4016-4027 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nuclear dynamics is incorporated into an efficient density matrix formalism of electronic dynamics which has been applied to molecular systems containing thousands of atoms. The formalism for the combined dynamics of electrons and nuclei is derived from the Dirac–Frenkel variational principle. The single electron reduced density matrices and the Glauber coherent states are used for the electronic and nuclear degrees of freedom, respectively. The new formalism is applicable to simulate the dynamics of large molecular systems. As an illustration of its validity, the formalism is employed to calculate the electron and nuclei dynamics of hydrogen molecules. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288374
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  • 4
    Electronic Resource
    Electronic Resource
    Variational energy band theory for polarons: Mapping polaron structure with the Toyozawa method (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 3159-3178 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this article we revisit from a contemporary perspective a classic problem of polaron theory in one space dimension following the variational approach originally taken by Toyozawa. Polaron structure is represented by variational surfaces giving the optimal values of the complete set of exciton and phonon amplitudes for every value of the joint exciton-phonon crystal momentum κ. Through this exfoliation of the exciton-phonon correlations comprising the polaron, characteristic small polaron, large polaron, and nearly free phonon structures are identified, and the manner in which these compete and/or coexist is examined in detail. Through such examination, the parameter space of the problem is mapped, with particular attention given to problematic areas such as the highly quantum mechanical weak-coupling regime, the highly nonlinear intermediate-coupling regime, and to the self-trapping transition that may be said to mark the onset of the strong-coupling regime. Through such examination of the complete parameter space at all κ, it is found that the common notion of a self-trapping phenomenon associated with κ=0 is a limiting aspect of a more general finite-κ phenomenon. Quantities such as phonon number distributions, complete ground state energy bands, and effective masses are obtained for all κ. The inverse problem of associating localized functions with the variational energy bands is addressed, with attention given to the concept of solitons and with the explicit construction of polaron Wannier states. The successes and failures of the Toyozawa method are assessed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474667
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  • 5
    Electronic Resource
    Electronic Resource
    Variational energy band theory for polarons: Mapping polaron structure with the Merrifield method (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 5622-5630 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we revisit from a contemporary perspective a classic problem of polaron theory following the variational approach originally taken by Merrifield. Polaron structure is represented by a variational surface giving the optimal values of the complete set of phonon amplitudes for every value of the joint exciton–phonon crystal momentum κ. Quantities such as complete ground state energy bands (all κ) and effective masses (κ=0) are obtained. The parameter space of the problem is mapped, with careful attention given to the self-trapping transition. Through this examination of the complete parameter space at all κ, it is found that the common notion of a sharp self-trapping phenomenon associated with κ=0 is a limiting aspect of a more general finite-κ phenomenon. The idea of polaron Wannier states is addressed briefly, and the properties of such states tied to characteristics of the polaron energy band. The successes and failures of the Merrifield method are assessed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473598
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  • 6
    Electronic Resource
    Electronic Resource
    On the Munn–Silbey approach to nonlocal exciton–phonon coupling (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2335-2345 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A canonical transformation method originally proposed by Munn and Silbey is used to partially diagonalize a model Hamiltonian which incorporates both local and nonlocal exciton–phonon coupling. At the heart of the method is a secular elimination principle which poses a difficult self-consistency problem. A limited form of this self-consistency problem was solved in an approximate fashion by primarily analytical methods in the original work of Munn and Silbey. We take a numerical approach, solving the general self-consistency problem to desired accuracy. Among the differences between our findings and those of the original work are polaron binding energies much larger and Debye–Waller factors much smaller than originally anticipated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466480
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  • 7
    Electronic Resource
    Electronic Resource
    Optical phase conjugation in InGaAs/GaAs multiple quantum wells at 1.06 μm wavelength (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 281-283 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The observation of phase conjugation in InGaAs/GaAs multiple quantum wells at 1.06 μm wavelength is reported on. The effective nonlinearity of the sample used in our experiments was measured to be χ(3)=10−7 esu. The nonlinearity is induced by the saturation absorption due to band filling and exciton bleaching. The saturation intensity is 1.3 kW/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110078
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  • 8
    Electronic Resource
    Electronic Resource
    Dependence of C60 Formation on Orientation of Graphite Lattice Plane (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 13440-13442 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100102a002
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  • 9
    Electronic Resource
    Electronic Resource
    The development of CO simulate control testing equipment (2004)
    Bingley : Emerald
    Aircraft engineering and aerospace technology 76 (2004), S. 573-576 
    Details
    ISSN: 0002-2667
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: For developing the control technique of air in the manned spacecraft cabin, the CO2 simulate control-testing equipment is developed to study the CO2 removal equipment in the carbon air. The developing process is introduced in this paper. On the basis of overall design, the authors emphasize the study of the cabin interface design and draw a conclusion that disposing the entrance of the gas at the same side of the cabin content the gas intimate mixing. In the design of the flow meter, using the plastic rotor can solve the problem of flow meter pressure loss which is too much by using the glass rotor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/00022660410565481
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  • 10
    Electronic Resource
    Electronic Resource
    Tribological Behavior of Nano-Silicate Mineral Powder as Lubrication Oil Additive (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 373-374 (Mar. 2008), p. 488-492 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The tribological behavior and the mechanism of nano-silicate mineral powder aslubrication oil additive were researched in the article. The tribological behavior of nano-silicatemineral powder with mass ratio 0.6% in lubrication oil 50CC was tested and compared with thelubrication oil 50CC’s by friction wear testing machine. The surface morphologies and elementarycompositions of grinding cracks were analyzed by Scanning Electron Microscope (SEM) and EnergyDispersive Spectrometer (EDS).The results showed that the friction coefficient is decreased 37.5%,and the lost mass of the upper proof sample reduces 68.75%, the down’s reduces 86.7%, after addingnano-silicate mineral as lubrication oil additive, by comparison to lubrication oil 50CC’s. Under thelubrication oil which has been putted nano-silicate mineral as additive, there is a repairing layerwhose material is different from basal body material on the grinding cracks; in addition, Si, Mg andother elements are deposited on the repairing layer. These state that nano-silicate mineral aslubrication oil additive possesses superior behavior of wear resistance, antiwear and self-repairingeffects
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/57/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.373-374.488.pdf
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