Application of a classical variational theory of chemical reaction rates to the fluorine + molecular hydrogen going to hydrogen fluoride + hydrogen and fluorine + hydrogen-deuterium going to deuterium fluoride (hydrogen fluoride) + hydrogen (deuterium) reactions.
Item
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Title
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Application of a classical variational theory of chemical reaction rates to the fluorine + molecular hydrogen going to hydrogen fluoride + hydrogen and fluorine + hydrogen-deuterium going to deuterium fluoride (hydrogen fluoride) + hydrogen (deuterium) reactions.
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Identifier
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AAI9605658
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identifier
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9605658
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Creator
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Rutenburg, Irina.
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Contributor
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Adviser: Gerald W. Koeppl
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Date
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1995
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Physical | Physics, Atmospheric Science
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Abstract
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The classical variational theory of chemical reaction rates gives the rate as the equilibrium flux of phase points through a trial surface in the phase space of the reaction system. The surface divides phase space into reactant and product regions and is varied to obtain a minimum upper bound for the rate of product formation. For bimolecular reactions of the type A + BC {dollar}\to{dollar} AB + C, Koeppl derived expressions for the microcanonical and canonical formulations of this theory which give the energy-dependent mean reaction cross section and canonical rate constant, respectively, for the most general dividing surface defined by configuration space coordinates (J. Chem. Phys. 87, 5746 (1987)). A numerical method which used the downhill simplex algorithm was developed to evaluate these quantities by determining coefficients (variational parameters) of terms in first, second, and third-order expansions of the dividing surface in the internal coordinates of the reaction system. The variational dividing surface so obtained defines a generalized transition state of the reaction system.;We present results for the application of this theory to the F + H{dollar}\sb2 \to{dollar} FH + H reaction for a series of potential energy functions in which the relationship between the angle dependent minimum potential energy for reaction and orientation angle of reactants varies systematically. Results are presented for a series of planar and curved dividing surfaces. The relationship between variational canonical rate constants and features of the potential energy function and features of different formulations of the dividing surface are studied.;We also present results for the first application of this variational theory to a reaction with a heteronuclear diatomic reactant. Several formulations of the dividing surface were used to study the F + DH {dollar}\to{dollar} FD(FH) + H(D) reactions. The best results were obtained for DS formulations which contain variational parameters which distinguish between reaction at each end of the heteronuclear reactant.;For both reactions, plots of the flux through variational dividing surfaces, that is, reactivity relief maps for transition state configurations of the reaction system, are used to describe the dynamical stereochemistry of the subject reactions. The accuracy of variational results for the variation of reactivity with orientation angle of the transition state is studied by comparing variational and classical mechanical trajectory results.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
