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  • 1
    Electronic Resource
    Electronic Resource
    Application of sensitivity analysis to the establishment of intermolecular potential functions (1991)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 113 (1991), S. 2020-2033 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00006a024
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  • 2
    Electronic Resource
    Electronic Resource
    Paradigms and algorithms for controlling molecular motion (1993)
    s.l. : American Chemical Society
    Accounts of chemical research 26 (1993), S. 496-501 
    Details
    ISSN: 1520-4898
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ar00033a007
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical dynamics and kinetics phenomena as revealed by sensitivity analysis techniques (1987)
    s.l. : American Chemical Society
    Chemical reviews 87 (1987), S. 101-112 
    Details
    ISSN: 1520-6890
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cr00077a006
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  • 4
    Electronic Resource
    Electronic Resource
    Statistical mechanics on the space of kinetic folding pathways (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 983-991 
    Details
    ISSN: 0392-6737
    Keywords: General, theoretical, and mathematical biophysics (including logic of biosystems, quantum biology, and relevant aspects of thermodynamics, information theory, cybernetics, and bionics) ; Molecular dynamics, conformational changes, and pattern recognition in biomolecules ; Physical chemistry of solutions of biological macromolecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary We introduce a general scheme to assign statistical weights to alla priori pathways in conformation space for an aggregate of interacting particles that undergoes a series of unimolecular events in a limited time frame. Illustrations of such systems are biopolymers that fold intramolecularly or macromolecules of biological relevance that exert their function onto themselves through a series of structural rearrangements under the severe time constraints imposed by enzymatic timing. We endow the space of kinetically controlled pathways with a regular measure induced by a stochastic process built upon a complex potential energy landscape. This process simulates the progressive and opportunistic exploration of basins of attraction of critical points in the molecular potential energy. The derivation is general and holds for any diffusion-like process subject to time constraints and governed by thermal fluctuations upon a complex energy landscape. Within this framework, the ensemble of physically relevant kinetically arrested states becomes a cross-section of the ensemble of pathways at a fixed instant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456786
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  • 5
    Electronic Resource
    Electronic Resource
    Discrete-continuum hybrid model for dynamics with applications: Desorption of adsorbates and relaxation of lattice inclusions (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4673-4686 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The paper presents and extends an earlier model for the relaxation dynamics within solids and desorption of adsorbates on surfaces. The model retains the discrete nature of the adsorbates while adopting a continuum representation for the solid. Extensive one-dimensional model calculations are carried out along with sample calculations in the two-dimensional case. Specifically, in the one-dimensional case, the formulation is for a diatom with harmonic intramolecular bond and a Morse potential between the diatom and the remaining solid as well as an atomic inclusion in a two-dimensional bulk solid. The excitation mechanisms are initial disturbances that take the system away from its equilibrium configuration and acoustic pulses incident on the molecule. An extensive parametric study is carried out by varying the width, amplitude, and frequency content of the pulse along with the strength of the Morse bond. These calculations permit an understanding of the roles of the various parameters in determining the relaxation rate associated with energy transfer and desorption processes for the case of the diatom bound to the solid surface as well as an atom as a guest in the solid. The observed physical phenomena span the linear to the highly nonlinear regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458707
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  • 6
    Electronic Resource
    Electronic Resource
    Optimal control of selective vibrational excitation of harmonic molecules: Analytic solution and restricted forms for the optimal fields (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2927-2937 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Analytic solutions of the optimal fields giving selective local excitation in harmonic molecules are presented, and calculated by a numerically stable algorithm. It is shown that the optimal fields can be decomposed into a finite number of monochromatic laser fields, with the following properties: (a) the number of component frequencies is equal to the number of normal modes of the molecule; (b) the component frequencies go to the molecular vibrational normal mode frequencies in the limit of low amplitude; (c) there is an inverse relationship between the amplitude of the fields (as controlled by the weighting factor for the field fluence term) and the time T at which the objective is reached; (d) there exists a limiting form for the optimal fields as the controlling time T→∞ (which had been observed empirically in previous work and now has a regorous mathematical basis). The intensity of the component laser fields, and thus the optimal field can be reduced to any desired level with a corresponding lengthening of the pulses. Thus by varying the design criteria one may determine a corresponding entire family of optimal fields with each member equivalently leading to the desired final local excitations. The optimization procedure clearly illustrates the trade off between optimal pulse length and amplitude. In order to try and achieve the control objectives with consideration of laboratory constraints on the laser fields a formalism is presented for designing the optimal fields with constrained functional forms. An illustration based on linear chain molecules shows that the objectives may be quite well achieved by using realistically constrained optimized fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457940
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of the interatomic potential from elastic differential cross sections at fixed energy: Functional sensitivity analysis approach (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 1519-1525 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Elastic differential cross sections in atomic crossed beam experiments contain detailed information about the underlying interatomic potentials. The functional sensitivity density of the cross sections with respect to the potential δσ(θ)/δV(R) reveals such information and has been implemented in an iterative inversion procedure, analogous to that of the Newton–Raphson technique. The stability of the inversion is achieved with the use of the regularization method of Tikhonov and Miller. It is shown that given a set of well resolved and noise-free differential cross section data within a limited angular range and given a reasonable starting reference potential, the recovered potential accurately resembles the desired one in the important region, i.e., the region to which the scattering data are sensitive. The region of importance depends upon the collision energy relative to the well depth of the potential under study; usually a higher collision energy penetrates deeper into the repulsive part of the potential and thus accordingly yields a more accurate potential in that part. The inversion procedure produces also a quality function indicating the well determined radial region. Moreover, the extracted potential is quite independent of the functional form of the reference potential in contrast to curve fitting approaches. As illustrations, the model inert gas systems He–Ne and Ne–Ar have been considered. For collision energies within an order of magnitude of the associated potential well depth, the attractive part of the potential can be determined to high precision provided that scattering data at small enough angles are available. On the other hand, the repulsive part of the potential must be scrutinized by high collision energy data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456094
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  • 8
    Electronic Resource
    Electronic Resource
    Optimal control of selective vibrational excitation in harmonic linear chain molecules (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6870-6883 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A formalism for designing an optical field for selective vibrational excitation in linear harmonic chain molecules is presented based on optimal control theory. The optimizing functional producing the field designs is flexible to allow for the imposition of desirable laboratory and theoretical constraints. The designed optimal fields, which successfully lead to local bond excitations, exhibit complex structure on the time scale of 10 fs. Analysis of the optimal fields shows a high degree of cooperativety between the temporal structure of the fields and the dynamical capabilities of the molecules. It is generally impossible using only spectral information to devise the optical field needed to selectively excite a local bond in a polyatomic molecule. These results explain why the previous intuitively based laboratory attempts at site specific chemistry have yielded disappointing results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454384
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  • 9
    Electronic Resource
    Electronic Resource
    Sensitivity analysis of mass effects in rotational energy transfer (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6322-6334 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper examines the sensitivity of rotationally inelastic integral state-to-state cross sections to variations in the masses of the collision partners. We investigate the helium-hydrogenic scattering system with its many physical isotopes and excellent ab initio potential. The collision dynamics are approximated by coupled states-exponential distorted wave (CS-EDW) theory and both cross sections and elementary sensitivity coefficients (partial derivatives of the cross sections with respect to the mass parameters) are calculated. In order to be able to properly interpret these results, we first generate conceptually and computationally simpler distorted wave (CS-DW) cross sections and elementary sensitivities. These perturbative results are analyzed using simple collisional concepts and models. In addition, we present functional forms which predict (or scale) the global behavior of DW cross sections through the mass parameter space. As a quantitative aid in linking EDW cross sections with the DW results, a new type of sensitivity coefficient is introduced which measures the sensitivity of a given EDW cross section to the variation of a single DW cross section or combination thereof.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454470
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  • 10
    Electronic Resource
    Electronic Resource
    Inverse problems in chemical dynamics: The calculation of inverse coefficients (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 1387-1394 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A general technique is described for gaining insight into inversion processes. Upon solving the equation of motion associated with a given physical model, specialized inverse coefficients are calculated to address questions on inverse modeling. The number of accessible independent inverse coefficients is shown to be directly related to the number of independent pieces of modeling data taken as available. Although the inverse coefficients do not in themselves form an inversion algorithm, they do give a quantitative measure of the importance of performing certain additional measurements for the ultimate purpose of inversion. The concepts are illustrated by some simple dynamical models. The calculations show that the normal forward sensitivities and the new inverse coefficients generally exhibit disparate behavior in accord with the differing physical quantities being addressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452226
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