You can find below the publication list of all members of the theoretical chemistry group at ENS. For the list of each individual member, please consult their personal webpage from the Members page.
1990 |
Role of Solvent Electronic Polarization in Electron-Transfer Processes Article de journal H J Kim; J T Hynes Journal of Physical Chemistry, 94 (7), p. 2736-2740, 1990, (cited By 75). @article{Kim19902736, title = {Role of Solvent Electronic Polarization in Electron-Transfer Processes}, author = {H J Kim and J T Hynes}, doi = {10.1021/j100370a004}, year = {1990}, date = {1990-01-01}, journal = {Journal of Physical Chemistry}, volume = {94}, number = {7}, pages = {2736-2740}, abstract = {The role of solvent electronic polarization in electron-transfer processes is investigated. The solvent electronic polarization is assumed to be instantaneously equilibrated to the quantum charge distribution of the transferring electron and the fluctuating solvent orientational polarization; this yields a nonlinear Schr\"{o}dinger equation for the electron wave function. The transition between nonadiabatic and adiabatic regimes is found to be governed by both electronic coupling and electronic polarization. Activation and reorganization free energies are obtained; in some regimes, they differ considerably from some conventional predictions. The physical origin and consequences of these features are described. textcopyright 1990 American Chemical Society.}, note = {cited By 75}, keywords = {}, pubstate = {published}, tppubtype = {article} } The role of solvent electronic polarization in electron-transfer processes is investigated. The solvent electronic polarization is assumed to be instantaneously equilibrated to the quantum charge distribution of the transferring electron and the fluctuating solvent orientational polarization; this yields a nonlinear Schrödinger equation for the electron wave function. The transition between nonadiabatic and adiabatic regimes is found to be governed by both electronic coupling and electronic polarization. Activation and reorganization free energies are obtained; in some regimes, they differ considerably from some conventional predictions. The physical origin and consequences of these features are described. textcopyright 1990 American Chemical Society. |
Fast Vibrational Relaxation for a Dipolar Molecule in a Polar Solvent Article de journal R M Whitnell; K R Wilson; J T Hynes Journal of Physical Chemistry, 94 (24), p. 8625-8628, 1990, (cited By 157). @article{Whitnell19908625, title = {Fast Vibrational Relaxation for a Dipolar Molecule in a Polar Solvent}, author = {R M Whitnell and K R Wilson and J T Hynes}, doi = {10.1021/j100387a002}, year = {1990}, date = {1990-01-01}, journal = {Journal of Physical Chemistry}, volume = {94}, number = {24}, pages = {8625-8628}, abstract = {Molecular dynamics computer simulations of CH 3 Cl, modeled as a vibrating diatomic, in water solvent reveal a rapid vibrational energy relaxation for the polar solute, over a wide range of initial vibrational excitations. A Landau-Teller formula is found to describe well the computed relaxation times. textcopyright 1990 American Chemical Society.}, note = {cited By 157}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular dynamics computer simulations of CH 3 Cl, modeled as a vibrating diatomic, in water solvent reveal a rapid vibrational energy relaxation for the polar solute, over a wide range of initial vibrational excitations. A Landau-Teller formula is found to describe well the computed relaxation times. textcopyright 1990 American Chemical Society. |
Dynamics of Ion Pair Interconversion in a Polar Solvent Article de journal G Ciccotti; M Ferrario; J T Hynes; R Kapral The Journal of Chemical Physics, 93 (10), p. 7137-7147, 1990, (cited By 158). @article{Ciccotti19907137, title = {Dynamics of Ion Pair Interconversion in a Polar Solvent}, author = {G Ciccotti and M Ferrario and J T Hynes and R Kapral}, doi = {10.1063/1.459437}, year = {1990}, date = {1990-01-01}, journal = {The Journal of Chemical Physics}, volume = {93}, number = {10}, pages = {7137-7147}, abstract = {The reaction rate and mechanism of the interconversion between a contact ion pair and solvent separated ion pair in model polar solvents is investigated by molecular dynamics (MD) simulation. The full rate constant for the model reaction is estimated from the product of the transition state theory (TST) rate constant, determined from the potential of mean force between the ions in an equilibrium solvent, and the transmission coefficient, which depends on the details of the dynamics. The collective character of the solvent motion in the reaction barrier crossing is examined in some detail, and the important role of solvent dynamics in causing the reaction rate to markedly deviate from the TST rate is discussed. The MD results are compared with the predictions of Kramers and Grote-Hynes theories. textcopyright 1990 American Institute of Physics.}, note = {cited By 158}, keywords = {}, pubstate = {published}, tppubtype = {article} } The reaction rate and mechanism of the interconversion between a contact ion pair and solvent separated ion pair in model polar solvents is investigated by molecular dynamics (MD) simulation. The full rate constant for the model reaction is estimated from the product of the transition state theory (TST) rate constant, determined from the potential of mean force between the ions in an equilibrium solvent, and the transmission coefficient, which depends on the details of the dynamics. The collective character of the solvent motion in the reaction barrier crossing is examined in some detail, and the important role of solvent dynamics in causing the reaction rate to markedly deviate from the TST rate is discussed. The MD results are compared with the predictions of Kramers and Grote-Hynes theories. textcopyright 1990 American Institute of Physics. |
1989 |
Dissociation of Remote Bonds by Overtone Excitation: A Model Study of Heavy-Atom Blocking Article de journal T Uzer; J T Hynes Chemical Physics, 139 (1), p. 163-170, 1989, (cited By 19). @article{Uzer1989163, title = {Dissociation of Remote Bonds by Overtone Excitation: A Model Study of Heavy-Atom Blocking}, author = {T Uzer and J T Hynes}, doi = {10.1016/0301-0104(89)90009-8}, year = {1989}, date = {1989-01-01}, journal = {Chemical Physics}, volume = {139}, number = {1}, pages = {163-170}, abstract = {We present a classical-mechanical study of model systems which allow the rupture of a weak bond subsequent to excitation of overtones in remote parts of the molecule. Our models are the linear chains HCCCX and HCMCX, where M is a heavy atom and the CX bond is weak. The ensuing mode-specificities and nonstatistical behavior are strongly affected by the presence of a heavy-atom blocker. textcopyright 1989.}, note = {cited By 19}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a classical-mechanical study of model systems which allow the rupture of a weak bond subsequent to excitation of overtones in remote parts of the molecule. Our models are the linear chains HCCCX and HCMCX, where M is a heavy atom and the CX bond is weak. The ensuing mode-specificities and nonstatistical behavior are strongly affected by the presence of a heavy-atom blocker. textcopyright 1989. |
Collinear Proton Transfer in a Symmetric Bihalide System Article de journal S Chapman; D P Ali; J T Hynes Chemical Physics, 136 (2), p. 297-309, 1989, (cited By 10). @article{Chapman1989297, title = {Collinear Proton Transfer in a Symmetric Bihalide System}, author = {S Chapman and D P Ali and J T Hynes}, doi = {10.1016/0301-0104(89)80054-0}, year = {1989}, date = {1989-01-01}, journal = {Chemical Physics}, volume = {136}, number = {2}, pages = {297-309}, abstract = {A semiclassical vibrationally adiabatic theory is applied to the collinear gas phase proton transfer reaction Cl- + HCl $rightarrow$ ClH + Cl-. It is found that tunneling is negligible in the reaction and that the principal dynamic features are governed by the deep potential for the reactants. Evidence is presented that quasiclassical trajectory dynamics is unreliable for this collinear system, in that the trajectories exhibit marked nonadiabaticity - i.e. complex formation in which there is significant energy transfer between the proton motion and the relative motion of the two chloride ions. It is argued that, by contrast, the quantum collinear reaction is adiabatic and direct in character. Comparison with recent experimental results suggests that development of a full three-dimensional theory may be necessary for an adequate picture of this reaction. textcopyright 1989.}, note = {cited By 10}, keywords = {}, pubstate = {published}, tppubtype = {article} } A semiclassical vibrationally adiabatic theory is applied to the collinear gas phase proton transfer reaction Cl- + HCl $rightarrow$ ClH + Cl-. It is found that tunneling is negligible in the reaction and that the principal dynamic features are governed by the deep potential for the reactants. Evidence is presented that quasiclassical trajectory dynamics is unreliable for this collinear system, in that the trajectories exhibit marked nonadiabaticity - i.e. complex formation in which there is significant energy transfer between the proton motion and the relative motion of the two chloride ions. It is argued that, by contrast, the quantum collinear reaction is adiabatic and direct in character. Comparison with recent experimental results suggests that development of a full three-dimensional theory may be necessary for an adequate picture of this reaction. textcopyright 1989. |
A Stochastic Theory of Chemical Reaction Rates. I. Formalism Article de journal B Gaveau; J T Hynes; R Kapral; M Moreau Journal of Statistical Physics, 56 (5-6), p. 879-893, 1989, (cited By 12). @article{Gaveau1989879, title = {A Stochastic Theory of Chemical Reaction Rates. I. Formalism}, author = {B Gaveau and J T Hynes and R Kapral and M Moreau}, doi = {10.1007/BF01016783}, year = {1989}, date = {1989-01-01}, journal = {Journal of Statistical Physics}, volume = {56}, number = {5-6}, pages = {879-893}, abstract = {A class of stochastic processes is studied that can be used to model elementary and complex chemical reactions composed of a series of several distinct steps. Formal correlation function expressions are directly computed for the stochastic model to yield the overall rate constant for the reaction. One of the main results is a formula connecting the overall rate constant to the rate constants characterizing the elementary steps of the reaction. textcopyright 1989 Plenum Publishing Corporation.}, note = {cited By 12}, keywords = {}, pubstate = {published}, tppubtype = {article} } A class of stochastic processes is studied that can be used to model elementary and complex chemical reactions composed of a series of several distinct steps. Formal correlation function expressions are directly computed for the stochastic model to yield the overall rate constant for the reaction. One of the main results is a formula connecting the overall rate constant to the rate constants characterizing the elementary steps of the reaction. textcopyright 1989 Plenum Publishing Corporation. |
A Stochastic Theory of Chemical Reaction Rates. II. Applications Article de journal B Gaveau; J T Hynes; R Kapral; M Moreau Journal of Statistical Physics, 56 (5-6), p. 895-910, 1989, (cited By 11). @article{Gaveau1989895, title = {A Stochastic Theory of Chemical Reaction Rates. II. Applications}, author = {B Gaveau and J T Hynes and R Kapral and M Moreau}, doi = {10.1007/BF01016784}, year = {1989}, date = {1989-01-01}, journal = {Journal of Statistical Physics}, volume = {56}, number = {5-6}, pages = {895-910}, abstract = {A formalism developed for the treatment of chainlike models of reaction dynamics is applied to simple reacting systems and generalized to treat a reaction with a branching process. The models can be solved exactly, and the overall rates of the reactions are studied as a function of the rates arising from different dynamical regimes involved in the microscopic mechanisms. textcopyright 1989 Plenum Publishing Corporation.}, note = {cited By 11}, keywords = {}, pubstate = {published}, tppubtype = {article} } A formalism developed for the treatment of chainlike models of reaction dynamics is applied to simple reacting systems and generalized to treat a reaction with a branching process. The models can be solved exactly, and the overall rates of the reactions are studied as a function of the rates arising from different dynamical regimes involved in the microscopic mechanisms. textcopyright 1989 Plenum Publishing Corporation. |
Constrained Reaction Coordinate Dynamics for the Simulation of Rare Events Article de journal E A Carter; G Ciccotti; J T Hynes; R Kapral Chemical Physics Letters, 156 (5), p. 472-477, 1989, (cited By 636). @article{Carter1989472, title = {Constrained Reaction Coordinate Dynamics for the Simulation of Rare Events}, author = {E A Carter and G Ciccotti and J T Hynes and R Kapral}, doi = {10.1016/S0009-2614(89)87314-2}, year = {1989}, date = {1989-01-01}, journal = {Chemical Physics Letters}, volume = {156}, number = {5}, pages = {472-477}, abstract = {A computationally efficient molecular dynamics method for estimating the rates of rare events that occur by activated processes is described. The system is constrained at "bottleneck" regions on a general many-body reaction coordinate in order to generate a biased configurational distribution. Suitable reweighting of this biased distribution, along with correct momentum distribution sampling, provides a new ensemble, the constrained-reaction-coordinate-dynamics ensemble, with which to study rare events of this type. Applications to chemical reaction rates are made. textcopyright 1989.}, note = {cited By 636}, keywords = {}, pubstate = {published}, tppubtype = {article} } A computationally efficient molecular dynamics method for estimating the rates of rare events that occur by activated processes is described. The system is constrained at "bottleneck" regions on a general many-body reaction coordinate in order to generate a biased configurational distribution. Suitable reweighting of this biased distribution, along with correct momentum distribution sampling, provides a new ensemble, the constrained-reaction-coordinate-dynamics ensemble, with which to study rare events of this type. Applications to chemical reaction rates are made. textcopyright 1989. |
Constrained Molecular Dynamics and the Mean Potential for an Ion Pair in a Polar Solvent Article de journal G Ciccotti; M Ferrario; J T Hynes; R Kapral Chemical Physics, 129 (2), p. 241-251, 1989, (cited By 213). @article{Ciccotti1989241, title = {Constrained Molecular Dynamics and the Mean Potential for an Ion Pair in a Polar Solvent}, author = {G Ciccotti and M Ferrario and J T Hynes and R Kapral}, doi = {10.1016/0301-0104(89)80010-2}, year = {1989}, date = {1989-01-01}, journal = {Chemical Physics}, volume = {129}, number = {2}, pages = {241-251}, abstract = {A constrained molecular dynamics (MD) method for the calculation of the potential of mean force is described, and applied to study the solvent-separated and contact ion pair equilibrium in a polar solvent. The method uses holonomic constraints on the MD to fix ion pair internuclear separation. The average force exerted on the ions by the solvent is computed as a function of ion separation, and the potential of mean force follows from an integration of the mean force. The ion pair mean potential, the reaction equilibrium constant and the solvent structure in the vicinity of the ions are examined for two model solvents with differing molecular dipole moments. The relevance of this study for the dynamics of the contact ion pair-solvent separated ion pair reaction is pointed out. textcopyright 1989.}, note = {cited By 213}, keywords = {}, pubstate = {published}, tppubtype = {article} } A constrained molecular dynamics (MD) method for the calculation of the potential of mean force is described, and applied to study the solvent-separated and contact ion pair equilibrium in a polar solvent. The method uses holonomic constraints on the MD to fix ion pair internuclear separation. The average force exerted on the ions by the solvent is computed as a function of ion separation, and the potential of mean force follows from an integration of the mean force. The ion pair mean potential, the reaction equilibrium constant and the solvent structure in the vicinity of the ions are examined for two model solvents with differing molecular dipole moments. The relevance of this study for the dynamics of the contact ion pair-solvent separated ion pair reaction is pointed out. textcopyright 1989. |
Radical Recombination Rate Constants from Gas to Liquid Phase Article de journal A G Zawadzki; J T Hynes Journal of Physical Chemistry, 93 (19), p. 7031-7036, 1989, (cited By 13). @article{Zawadzki19897031, title = {Radical Recombination Rate Constants from Gas to Liquid Phase}, author = {A G Zawadzki and J T Hynes}, doi = {10.1021/j100356a030}, year = {1989}, date = {1989-01-01}, journal = {Journal of Physical Chemistry}, volume = {93}, number = {19}, pages = {7031-7036}, abstract = {A simple connection formula is successfully used to predict radical recombination rate constants, kr, from gas- to liquid-phase densities. The formula ingredients are the low-pressure termolecular rate constant, krtextdegree, which in general has radical complex (RC) and energy-transfer (ET) contributions, the transition state theory rate constant, kr TST, and the rate constant for diffusion-controlled recombination, kr D. Application to iodine recombination accounts well for experimental observations of kr variation with buffer gas density (and complexity) and temperature and emphasizes the importance of the RC mechanism. Application to methyl radical recombination highlights the importance of internal degrees of freedom coupled to the reaction coordinate in accounting for broad plateau behavior in experimental rates. textcopyright 1989 American Chemical Society.}, note = {cited By 13}, keywords = {}, pubstate = {published}, tppubtype = {article} } A simple connection formula is successfully used to predict radical recombination rate constants, kr, from gas- to liquid-phase densities. The formula ingredients are the low-pressure termolecular rate constant, krtextdegree, which in general has radical complex (RC) and energy-transfer (ET) contributions, the transition state theory rate constant, kr TST, and the rate constant for diffusion-controlled recombination, kr D. Application to iodine recombination accounts well for experimental observations of kr variation with buffer gas density (and complexity) and temperature and emphasizes the importance of the RC mechanism. Application to methyl radical recombination highlights the importance of internal degrees of freedom coupled to the reaction coordinate in accounting for broad plateau behavior in experimental rates. textcopyright 1989 American Chemical Society. |
Solute-Dependent Solvent Force Constants for Ion Pairs and Neutral Pairs in a Polar Solvent Article de journal E A Carter; J T Hynes Journal of Physical Chemistry, 93 (6), p. 2184-2187, 1989, (cited By 183). @article{Carter19892184, title = {Solute-Dependent Solvent Force Constants for Ion Pairs and Neutral Pairs in a Polar Solvent}, author = {E A Carter and J T Hynes}, doi = {10.1021/j100343a002}, year = {1989}, date = {1989-01-01}, journal = {Journal of Physical Chemistry}, volume = {93}, number = {6}, pages = {2184-2187}, abstract = {The solvent force constants k characterizing the fluctuations of a polar solvent in the presence of a solute ion pair A+B- and a neutral pair AB are determined by molecular dynamics simulation. The origin of the observed difference in the k values and the consequences for electron-transfer rate-reaction free energy gap behavior are discussed. textcopyright 1989 American Chemical Society.}, note = {cited By 183}, keywords = {}, pubstate = {published}, tppubtype = {article} } The solvent force constants k characterizing the fluctuations of a polar solvent in the presence of a solute ion pair A+B- and a neutral pair AB are determined by molecular dynamics simulation. The origin of the observed difference in the k values and the consequences for electron-transfer rate-reaction free energy gap behavior are discussed. textcopyright 1989 American Chemical Society. |
Polar Solvent Contributions to Activation Parameters for Model Ionic Reactions Article de journal T Morita; B M Ladanyi; J T Hynes Journal of Physical Chemistry, 93 (4), p. 1386-1392, 1989, (cited By 33). @article{Morita19891386, title = {Polar Solvent Contributions to Activation Parameters for Model Ionic Reactions}, author = {T Morita and B M Ladanyi and J T Hynes}, doi = {10.1021/j100341a041}, year = {1989}, date = {1989-01-01}, journal = {Journal of Physical Chemistry}, volume = {93}, number = {4}, pages = {1386-1392}, abstract = {Transition-state-theory (TST) transfer activation parameters for model ionic reactions A+ + B- $rightarrow$ products in model polar solvents (water and chloroform) are calculated via reference linearized hypernetted chain theory of intermolecular structure. Transfer activation free energies ($DeltaDelta$G$not =$), enthalpies ($DeltaDelta$H$not =$), entropies ($DeltaDelta$S$not =$), and activation volumes ($Delta$V$not =$) are studied as functions of ionic sizes and the location of the transition state. We find that the molecular theory transfer activation parameters often differ considerably from dielectric continuum theory predictions. For example, for certain A+ + B- reactions the molecular theory predicts orders of magnitude greater solvent-induced rate enhancement than the continuum theory. In addition, molecular $Delta$V$not =$ values, which reflect polar solvent electrostrictive effects, significantly exceed continuum predictions. Nonetheless, qualitative similarities between the predictions of the two theories are often observed; an example is an approximate linear correlation between $DeltaDelta$S$not =$ and $Delta$V$not =$ values. For weak electrostatic interactions, e.g., when reactant ions have low charge density, it is found that electrostatic and hard-sphere solvent structural contributions to activation parameters can be comparable. It is also pointed out that significant pressure variation of $Delta$V$not =$ should be accounted for in isolating possible dynamic solvent-induced breakdown of TST rate predictions. textcopyright 1989 American Chemical Society.}, note = {cited By 33}, keywords = {}, pubstate = {published}, tppubtype = {article} } Transition-state-theory (TST) transfer activation parameters for model ionic reactions A+ + B- $rightarrow$ products in model polar solvents (water and chloroform) are calculated via reference linearized hypernetted chain theory of intermolecular structure. Transfer activation free energies ($DeltaDelta$G$not =$), enthalpies ($DeltaDelta$H$not =$), entropies ($DeltaDelta$S$not =$), and activation volumes ($Delta$V$not =$) are studied as functions of ionic sizes and the location of the transition state. We find that the molecular theory transfer activation parameters often differ considerably from dielectric continuum theory predictions. For example, for certain A+ + B- reactions the molecular theory predicts orders of magnitude greater solvent-induced rate enhancement than the continuum theory. In addition, molecular $Delta$V$not =$ values, which reflect polar solvent electrostrictive effects, significantly exceed continuum predictions. Nonetheless, qualitative similarities between the predictions of the two theories are often observed; an example is an approximate linear correlation between $DeltaDelta$S$not =$ and $Delta$V$not =$ values. For weak electrostatic interactions, e.g., when reactant ions have low charge density, it is found that electrostatic and hard-sphere solvent structural contributions to activation parameters can be comparable. It is also pointed out that significant pressure variation of $Delta$V$not =$ should be accounted for in isolating possible dynamic solvent-induced breakdown of TST rate predictions. textcopyright 1989 American Chemical Society. |
Nonequilibrium Solvation Effects on Reaction Rates for Model S N 2 Reactions in Water Article de journal B J Gertner; K R Wilson; J T Hynes The Journal of Chemical Physics, 90 (7), p. 3537-3558, 1989, (cited By 287). @article{Gertner19893537, title = {Nonequilibrium Solvation Effects on Reaction Rates for Model S N 2 Reactions in Water}, author = {B J Gertner and K R Wilson and J T Hynes}, doi = {10.1063/1.455864}, year = {1989}, date = {1989-01-01}, journal = {The Journal of Chemical Physics}, volume = {90}, number = {7}, pages = {3537-3558}, abstract = {Molecular dynamics (MD) simulations of the model S N 2 reaction Cl - + CH 3 Cl$rightarrow$ClH 3 +Cl - in water, and variants thereof, are presented. The resulting transmission coefficients K, that measure the deviations of the rates from the transition state theory (TST) rate predictions due to solvent-induced recrossings, are used to assess the validity of the generalized Langevin equation (GLE)-based Grote-Hynes (GH) theory. The GH predictions are found to agree with the MD results to within the error bars of the calculations for each of the 12 cases examined. This agreement extends from the nonadiabatic regime, where solvent molecule motions are unimportant and $kappa$ is determined by static solvent configurations at the transition state, into the polarization caging regime, where solvent motion is critical in determining $kappa$. In contrast, the Kramers theory predictions for $kappa$ fall well below the simulation results. The friction kernel in the GLE used to evaluate the GH ^evalues is determined, from MD simulation, by a fixed-particle time correlation function of the force at the transition state. When this is expressed as a (Fourier) friction spectrum in frequency, marked similarities to the pure solvent spectrum are observed, and are used to identify the water solvent motions that determine the transmission coefficient $kappa$. The deviations of $kappa$ from unity, the TST value, are dominated by solvent motions (translational and reorientational) which on the time scale of the recrossings are essentially static configurations. The deviations from the frozen solvent, nonadiabatic limit values $kappa$ NA are dominated by the hinderd rotations (librations). Finally, the underlying assumptions of the GLE and the GH theory are discussed within the context of the simulation results. textcopyright 1989 American Institute of Physics.}, note = {cited By 287}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular dynamics (MD) simulations of the model S N 2 reaction Cl - + CH 3 Cl$rightarrow$ClH 3 +Cl - in water, and variants thereof, are presented. The resulting transmission coefficients K, that measure the deviations of the rates from the transition state theory (TST) rate predictions due to solvent-induced recrossings, are used to assess the validity of the generalized Langevin equation (GLE)-based Grote-Hynes (GH) theory. The GH predictions are found to agree with the MD results to within the error bars of the calculations for each of the 12 cases examined. This agreement extends from the nonadiabatic regime, where solvent molecule motions are unimportant and $kappa$ is determined by static solvent configurations at the transition state, into the polarization caging regime, where solvent motion is critical in determining $kappa$. In contrast, the Kramers theory predictions for $kappa$ fall well below the simulation results. The friction kernel in the GLE used to evaluate the GH ^evalues is determined, from MD simulation, by a fixed-particle time correlation function of the force at the transition state. When this is expressed as a (Fourier) friction spectrum in frequency, marked similarities to the pure solvent spectrum are observed, and are used to identify the water solvent motions that determine the transmission coefficient $kappa$. The deviations of $kappa$ from unity, the TST value, are dominated by solvent motions (translational and reorientational) which on the time scale of the recrossings are essentially static configurations. The deviations from the frozen solvent, nonadiabatic limit values $kappa$ NA are dominated by the hinderd rotations (librations). Finally, the underlying assumptions of the GLE and the GH theory are discussed within the context of the simulation results. textcopyright 1989 American Institute of Physics. |
Molecular Dynamics Simulation of Electron-Transfer Reactions in Solution Article de journal D A Zichi; G Ciccotti; J T Hynes; M Ferrario Journal of Physical Chemistry, 93 (17), p. 6261-6265, 1989, (cited By 130). @article{Zichi19896261, title = {Molecular Dynamics Simulation of Electron-Transfer Reactions in Solution}, author = {D A Zichi and G Ciccotti and J T Hynes and M Ferrario}, doi = {10.1021/j100354a001}, year = {1989}, date = {1989-01-01}, journal = {Journal of Physical Chemistry}, volume = {93}, number = {17}, pages = {6261-6265}, abstract = {Molecular dynamics simulation results are presented for model electronically adiabatic electron-transfer reactions in a model polar solvent. Transmission coefficients $kappa$ characterizing the departure of the rates from the Marcus theory predictions are determined, and theoretical approaches to predicting $kappa$ in terms of solvent dynamics are examined. textcopyright 1989 American Chemical Society.}, note = {cited By 130}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular dynamics simulation results are presented for model electronically adiabatic electron-transfer reactions in a model polar solvent. Transmission coefficients $kappa$ characterizing the departure of the rates from the Marcus theory predictions are determined, and theoretical approaches to predicting $kappa$ in terms of solvent dynamics are examined. textcopyright 1989 American Chemical Society. |
A Dynamical Theory of Nonadiabatic Proton and Hydrogen Atom Transfer Reaction Rates in Solution Article de journal D Borgis; S Lee; J T Hynes Chemical Physics Letters, 162 (1-2), p. 19-26, 1989, (cited By 218). @article{Borgis198919, title = {A Dynamical Theory of Nonadiabatic Proton and Hydrogen Atom Transfer Reaction Rates in Solution}, author = {D Borgis and S Lee and J T Hynes}, doi = {10.1016/0009-2614(89)85059-6}, year = {1989}, date = {1989-01-01}, journal = {Chemical Physics Letters}, volume = {162}, number = {1-2}, pages = {19-26}, abstract = {A dynamical theory for the rate constant k of hydrogen atom and proton transfer reactions in solution is presented for the nonadiabatic limit, where reaction is dominated by tunneling. Coupling and splitting fluctuation effects arising from intramolecular vibrational and solvent fluctuations are included in the description. Limiting regime analytic results for k are presented for high and low temperature and for weak and strong solvation. Differences between proton and hydrogen atom transfers are indicated, as are the contrasts with electron transfer rates. textcopyright 1989.}, note = {cited By 218}, keywords = {}, pubstate = {published}, tppubtype = {article} } A dynamical theory for the rate constant k of hydrogen atom and proton transfer reactions in solution is presented for the nonadiabatic limit, where reaction is dominated by tunneling. Coupling and splitting fluctuation effects arising from intramolecular vibrational and solvent fluctuations are included in the description. Limiting regime analytic results for k are presented for high and low temperature and for weak and strong solvation. Differences between proton and hydrogen atom transfers are indicated, as are the contrasts with electron transfer rates. textcopyright 1989. |
1988 |
Non-Equilibrium Solvation in S N 1 and S N 2 Reactions in Polar Solvents Article de journal B J Gertner; K R Wilson; D A Zichi; S Lee; J T Hynes Faraday Discussions of the Chemical Society, 85 , p. 297-308, 1988, (cited By 32). @article{Gertner1988297, title = {Non-Equilibrium Solvation in S N 1 and S N 2 Reactions in Polar Solvents}, author = {B J Gertner and K R Wilson and D A Zichi and S Lee and J T Hynes}, doi = {10.1039/DC9888500297}, year = {1988}, date = {1988-01-01}, journal = {Faraday Discussions of the Chemical Society}, volume = {85}, pages = {297-308}, abstract = {In the standard transition-state theory (TST) view of the role of the polar solvent in ionic reactions, the solvent is implicitly assumed always to be in equilibrium with the intrinsic reaction system at each point along the reaction coordinate. However, if there is insufficient time for the solvent molecules to so equilibrate, there will be non-equilibrium solvation effects. These cause a breakdown in the TST predictions for the reaction rate. These effects are analytically described via van der Zwan-Hynes theory and Grote-Hynes theory and examined via a molecular-dynamics simulation of a model Cl - +CH 3 Cl S N 2 reaction in water, and analytically for a model S N 1 dissociation in water. Finally, a solution-phase reaction-path Hamiltonian theory is described to investigate anharmonic effects on model S N 2 reactions.}, note = {cited By 32}, keywords = {}, pubstate = {published}, tppubtype = {article} } In the standard transition-state theory (TST) view of the role of the polar solvent in ionic reactions, the solvent is implicitly assumed always to be in equilibrium with the intrinsic reaction system at each point along the reaction coordinate. However, if there is insufficient time for the solvent molecules to so equilibrate, there will be non-equilibrium solvation effects. These cause a breakdown in the TST predictions for the reaction rate. These effects are analytically described via van der Zwan-Hynes theory and Grote-Hynes theory and examined via a molecular-dynamics simulation of a model Cl - +CH 3 Cl S N 2 reaction in water, and analytically for a model S N 1 dissociation in water. Finally, a solution-phase reaction-path Hamiltonian theory is described to investigate anharmonic effects on model S N 2 reactions. |
General Discussion Article de journal P G Wolynes; P Suppan; J T Hynes; Y Marcus; J G Dawber; O Kajimoto; M C R Symons; D J Yarwood; G R Fleming; H L Friedman; P Barbara; J Yarwood; D E Logan Faraday Discussions of the Chemical Society, 85 , p. 225-236, 1988, (cited By 0). @article{Wolynes1988225, title = {General Discussion}, author = {P G Wolynes and P Suppan and J T Hynes and Y Marcus and J G Dawber and O Kajimoto and M C R Symons and D J Yarwood and G R Fleming and H L Friedman and P Barbara and J Yarwood and D E Logan}, doi = {10.1039/DC9888500225}, year = {1988}, date = {1988-01-01}, journal = {Faraday Discussions of the Chemical Society}, volume = {85}, pages = {225-236}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
General Discussion Article de journal P Barbara; J T Hynes; D Chandler; M C R Symons; M H Abraham; C F Wells; M Henchman; M J Blandamer; D Bush; K H Halawani; J Schroeder; J Troe; P G Wolynes; P Suppan; H L Friedman; D G Hall Faraday Discussions of the Chemical Society, 85 , p. 341-364, 1988, (cited By 3). @article{Barbara1988341, title = {General Discussion}, author = {P Barbara and J T Hynes and D Chandler and M C R Symons and M H Abraham and C F Wells and M Henchman and M J Blandamer and D Bush and K H Halawani and J Schroeder and J Troe and P G Wolynes and P Suppan and H L Friedman and D G Hall}, doi = {10.1039/DC9888500341}, year = {1988}, date = {1988-01-01}, journal = {Faraday Discussions of the Chemical Society}, volume = {85}, pages = {341-364}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
General Discussion Article de journal D Chandler; H L Friedman; J T Hynes; P Suppan; B E Conway; Y Marcus; M C R Symons; M L Klein; W A P Luck; A D Buckingham; B J Howard; P Kebarle; J B F N Engberts; M H Abraham; M Henchman; A A Viggiano; J F Paulson; F Dale; C Deakyne; S Tomoda; P G Wolynes; J P Devlin; P F Barbara; O Kajimoto; J P Simons Faraday Discussions of the Chemical Society, 85 , p. 77-106, 1988, (cited By 2). @article{Chandler198877, title = {General Discussion}, author = {D Chandler and H L Friedman and J T Hynes and P Suppan and B E Conway and Y Marcus and M C R Symons and M L Klein and W A P Luck and A D Buckingham and B J Howard and P Kebarle and J B F N Engberts and M H Abraham and M Henchman and A A Viggiano and J F Paulson and F Dale and C Deakyne and S Tomoda and P G Wolynes and J P Devlin and P F Barbara and O Kajimoto and J P Simons}, doi = {10.1039/DC9888500077}, year = {1988}, date = {1988-01-01}, journal = {Faraday Discussions of the Chemical Society}, volume = {85}, pages = {77-106}, note = {cited By 2}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Solution Reaction Path Hamiltonian for Reactions in Polar Solvents. I. Formulation Article de journal S Lee; J T Hynes The Journal of Chemical Physics, 88 (11), p. 6853-6862, 1988, (cited By 158). @article{Lee19886853, title = {Solution Reaction Path Hamiltonian for Reactions in Polar Solvents. I. Formulation}, author = {S Lee and J T Hynes}, doi = {10.1063/1.454383}, year = {1988}, date = {1988-01-01}, journal = {The Journal of Chemical Physics}, volume = {88}, number = {11}, pages = {6853-6862}, abstract = {A solution reaction path Hamiltonian (SRPH) is constructed for heavy particle charge transfer reactions in a nondissipative polar solvent. This formulation includes anharmonicities arising from, e.g., potential anharmonicity and reaction path curvature. The SRPH is used in conjunction with variational transition state theory (VTST) to obtain an expression for the reaction rate constant. This expression generalizes the van der Zwan-Hynes rate theory to include the influence of anharmonic effects as well as nonequilibrium solvation. A discussion of the reaction path in solution and its departure from an equilibrium solvation perspective is given. textcopyright 1988 American Institute of Physics.}, note = {cited By 158}, keywords = {}, pubstate = {published}, tppubtype = {article} } A solution reaction path Hamiltonian (SRPH) is constructed for heavy particle charge transfer reactions in a nondissipative polar solvent. This formulation includes anharmonicities arising from, e.g., potential anharmonicity and reaction path curvature. The SRPH is used in conjunction with variational transition state theory (VTST) to obtain an expression for the reaction rate constant. This expression generalizes the van der Zwan-Hynes rate theory to include the influence of anharmonic effects as well as nonequilibrium solvation. A discussion of the reaction path in solution and its departure from an equilibrium solvation perspective is given. textcopyright 1988 American Institute of Physics. |
Solution Reaction Path Hamiltonian for Reactions in Polar Solvents. II. Applications Article de journal S Lee; J T Hynes The Journal of Chemical Physics, 88 (11), p. 6863-6869, 1988, (cited By 61). @article{Lee19886863, title = {Solution Reaction Path Hamiltonian for Reactions in Polar Solvents. II. Applications}, author = {S Lee and J T Hynes}, doi = {10.1063/1.454747}, year = {1988}, date = {1988-01-01}, journal = {The Journal of Chemical Physics}, volume = {88}, number = {11}, pages = {6863-6869}, abstract = {The solution reaction path Hamiltonian (SRPH) developed in the previous paper is applied to model SN2 and ionic dissociation reactions in water solvent. The solution reaction paths are determined and show marked deviations from a standard equilibrium solvation picture. The impact of potential anharmonicities, reaction path curvature, and varying solvent mass on the rate constant is calculated via the variational transition state theory approach of I, and the deviations from harmonic van der Zwan-Hynes (ZH) theory are calculated. Typically only minor deviations from ZH theory are found. The reasons for this are discussed. textcopyright 1988 American Institute of Physics.}, note = {cited By 61}, keywords = {}, pubstate = {published}, tppubtype = {article} } The solution reaction path Hamiltonian (SRPH) developed in the previous paper is applied to model SN2 and ionic dissociation reactions in water solvent. The solution reaction paths are determined and show marked deviations from a standard equilibrium solvation picture. The impact of potential anharmonicities, reaction path curvature, and varying solvent mass on the rate constant is calculated via the variational transition state theory approach of I, and the deviations from harmonic van der Zwan-Hynes (ZH) theory are calculated. Typically only minor deviations from ZH theory are found. The reasons for this are discussed. textcopyright 1988 American Institute of Physics. |
A Dynamical Theory of Unimolecular Ionic Dissociation Reactions in Polar Solvents Article de journal D A Zichi; J T Hynes The Journal of Chemical Physics, 88 (4), p. 2513-2525, 1988, (cited By 48). @article{Zichi19882513, title = {A Dynamical Theory of Unimolecular Ionic Dissociation Reactions in Polar Solvents}, author = {D A Zichi and J T Hynes}, doi = {10.1063/1.454030}, year = {1988}, date = {1988-01-01}, journal = {The Journal of Chemical Physics}, volume = {88}, number = {4}, pages = {2513-2525}, abstract = {A dynamical theory for the rates of unimolecular dissociations in polar solvents is constructed. Two classes of dissociation reactions, with dipolar and ionic transition states, are considered, and the theory is illustrated for a generalized continuum model water solvent. The rate of charge variation along the reaction coordinate is found to play a central role. Deviations from equilibrium solvation transition state theory predictions are found and discussed. Two nonequilibrium solvation regimes-nonadiabatic solvation and polarization caging-occur, and their appearance is connected to whether the solvated transition state has a reactant-like or product-like charge distribution. textcopyright 1988 American Institute of Physics.}, note = {cited By 48}, keywords = {}, pubstate = {published}, tppubtype = {article} } A dynamical theory for the rates of unimolecular dissociations in polar solvents is constructed. Two classes of dissociation reactions, with dipolar and ionic transition states, are considered, and the theory is illustrated for a generalized continuum model water solvent. The rate of charge variation along the reaction coordinate is found to play a central role. Deviations from equilibrium solvation transition state theory predictions are found and discussed. Two nonequilibrium solvation regimes-nonadiabatic solvation and polarization caging-occur, and their appearance is connected to whether the solvated transition state has a reactant-like or product-like charge distribution. textcopyright 1988 American Institute of Physics. |
1987 |
Molecular Dynamics of a Model S N 2 Reaction in Water Article de journal J P Bergsma; B J Gertner; K R Wilson; J T Hynes The Journal of Chemical Physics, 86 (3), p. 1356-1376, 1987, (cited By 281). @article{Bergsma19871356, title = {Molecular Dynamics of a Model S N 2 Reaction in Water}, author = {J P Bergsma and B J Gertner and K R Wilson and J T Hynes}, doi = {10.1063/1.452224}, year = {1987}, date = {1987-01-01}, journal = {The Journal of Chemical Physics}, volume = {86}, number = {3}, pages = {1356-1376}, abstract = {Molecular dynamics are computed for a model S N 2 reaction Cl - +CH 3 Cl$rightarrow$ClCH 3 +Cl - in water and are found to be strongly dependent on the instantaneous local configuration of the solvent at the transition state barrier. There are significant deviations from the simple picture of passage over a free energy barrier in the reaction coordinate, and thus, a marked departure from transition state theory occurs in the form of barrier recrossings. Factors controlling the dynamics are discussed, and, in particular, the rate of change of atomic charge distribution along the reaction coordinate is found to have a major effect on the dynamics. A simple frozen solvent theory involving nonadiabatic solvation is presented which can predict the outcome of a particular reaction trajectory by considering only the interaction with the solvent of the reaction system at the gas-phase transition barrier. The frozen solvent theory also gives the transmission coefficient $kappa$ needed to make the transition state theory rate agree with the outcome of the molecular dynamics trajectories. This theoretical $kappa$ value, which is the implementation for the S N 2 reaction of the van der Zwan-Hynes nonadiabatic solvation transmission coefficient, is in good agreement with the trajectory results. In contrast, a Kramers theory description fails dramatically. textcopyright 1987 American Institute of Physics.}, note = {cited By 281}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular dynamics are computed for a model S N 2 reaction Cl - +CH 3 Cl$rightarrow$ClCH 3 +Cl - in water and are found to be strongly dependent on the instantaneous local configuration of the solvent at the transition state barrier. There are significant deviations from the simple picture of passage over a free energy barrier in the reaction coordinate, and thus, a marked departure from transition state theory occurs in the form of barrier recrossings. Factors controlling the dynamics are discussed, and, in particular, the rate of change of atomic charge distribution along the reaction coordinate is found to have a major effect on the dynamics. A simple frozen solvent theory involving nonadiabatic solvation is presented which can predict the outcome of a particular reaction trajectory by considering only the interaction with the solvent of the reaction system at the gas-phase transition barrier. The frozen solvent theory also gives the transmission coefficient $kappa$ needed to make the transition state theory rate agree with the outcome of the molecular dynamics trajectories. This theoretical $kappa$ value, which is the implementation for the S N 2 reaction of the van der Zwan-Hynes nonadiabatic solvation transmission coefficient, is in good agreement with the trajectory results. In contrast, a Kramers theory description fails dramatically. textcopyright 1987 American Institute of Physics. |
Nonadiabatic Solvation Model for S N 2 Reactions in Polar Solvents Article de journal B J Gertner; J P Bergsma; K R Wilson; S Lee; J T Hynes The Journal of Chemical Physics, 86 (3), p. 1377-1386, 1987, (cited By 149). @article{Gertner19871377, title = {Nonadiabatic Solvation Model for S N 2 Reactions in Polar Solvents}, author = {B J Gertner and J P Bergsma and K R Wilson and S Lee and J T Hynes}, doi = {10.1063/1.452225}, year = {1987}, date = {1987-01-01}, journal = {The Journal of Chemical Physics}, volume = {86}, number = {3}, pages = {1377-1386}, abstract = {An analytic theory for S N 2 reactions in polar solvents in the nonadiabatic solvation limit is presented and used to interpret the computer simulation results of the preceding paper by Bergsma et al. The theory is based on the nonadiabatic solvation limit of previous studies by van der Zwan and Hynes and incorporates the solvent approximately but explicitly via a coordinate additional to the intrinsic reaction coordinate. Central results include: an explicit expression for the reaction transmission coefficient $kappa$, the dependence of reaction probability on kinetic energy, the interpretation of $kappa$ in terms of nonequilibrium solvation entropy effects, and the deviation of the reaction coordinate from that assumed in the standard equilibrium solvation transition state theory view of the reaction. textcopyright 1987 American Institute of Physics.}, note = {cited By 149}, keywords = {}, pubstate = {published}, tppubtype = {article} } An analytic theory for S N 2 reactions in polar solvents in the nonadiabatic solvation limit is presented and used to interpret the computer simulation results of the preceding paper by Bergsma et al. The theory is based on the nonadiabatic solvation limit of previous studies by van der Zwan and Hynes and incorporates the solvent approximately but explicitly via a coordinate additional to the intrinsic reaction coordinate. Central results include: an explicit expression for the reaction transmission coefficient $kappa$, the dependence of reaction probability on kinetic energy, the interpretation of $kappa$ in terms of nonequilibrium solvation entropy effects, and the deviation of the reaction coordinate from that assumed in the standard equilibrium solvation transition state theory view of the reaction. textcopyright 1987 American Institute of Physics. |
1986 |
A Mechanism for CH Vibrational Relaxation in Alkanes Article de journal J S Hutchinson; J T Hynes; W P Reinhardt Journal of Physical Chemistry, 90 (16), p. 3528-3532, 1986, (cited By 42). @article{Hutchinson19863528, title = {A Mechanism for CH Vibrational Relaxation in Alkanes}, author = {J S Hutchinson and J T Hynes and W P Reinhardt}, year = {1986}, date = {1986-01-01}, journal = {Journal of Physical Chemistry}, volume = {90}, number = {16}, pages = {3528-3532}, abstract = {A simple but realistic model is presented for the vibrational motions which contribute to the relaxation of excited CH stretches in a series of alkanes. The mechanism for energy flow is proposed to be a 2-1 nonlinear Fermi resonance between the CH stretch and a local HCC bending mode. The excitation of the HCC bend results in the excitation of several normal-mode vibrations, including the two "terminal rocking" modes of the CH group. Relaxation of the initial excitation arises from the overlap of these nonlinear resonances. textcopyright 1986 American Chemical Society.}, note = {cited By 42}, keywords = {}, pubstate = {published}, tppubtype = {article} } A simple but realistic model is presented for the vibrational motions which contribute to the relaxation of excited CH stretches in a series of alkanes. The mechanism for energy flow is proposed to be a 2-1 nonlinear Fermi resonance between the CH stretch and a local HCC bending mode. The excitation of the HCC bend results in the excitation of several normal-mode vibrations, including the two "terminal rocking" modes of the CH group. Relaxation of the initial excitation arises from the overlap of these nonlinear resonances. textcopyright 1986 American Chemical Society. |
Dynamics of the A + BC Reaction in Solution Article de journal J P Bergsma; P M Edelsten; B J Gertner; K R Huber; J R Reimers; K R Wilson; S M Wu; J T Hynes Chemical Physics Letters, 123 (5), p. 394-398, 1986, (cited By 25). @article{Bergsma1986394, title = {Dynamics of the A + BC Reaction in Solution}, author = {J P Bergsma and P M Edelsten and B J Gertner and K R Huber and J R Reimers and K R Wilson and S M Wu and J T Hynes}, doi = {10.1016/0009-2614(86)80029-X}, year = {1986}, date = {1986-01-01}, journal = {Chemical Physics Letters}, volume = {123}, number = {5}, pages = {394-398}, abstract = {Molecular dynamics are computed for A+BC $rightarrow$ AB+C in a rare gas solvent. Transition state theory is valid. For $pm$ 0.02 ps about the barrier, reaction dynamics are essentially the same as without solvent. Reactive trajectories are translationally special over $approx$ $pm$ 0.02 ps, rotationally over $approx$ $pm$ 0.5 ps, and vibrationally over $>$ 100ps. textcopyright 1986.}, note = {cited By 25}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular dynamics are computed for A+BC $rightarrow$ AB+C in a rare gas solvent. Transition state theory is valid. For $pm$ 0.02 ps about the barrier, reaction dynamics are essentially the same as without solvent. Reactive trajectories are translationally special over $approx$ $pm$ 0.02 ps, rotationally over $approx$ $pm$ 0.5 ps, and vibrationally over $>$ 100ps. textcopyright 1986. |
Outer-Sphere Electron-Transfer Reactions and Frequency-Dependent Friction Article de journal J T Hynes Journal of Physical Chemistry, 90 (16), p. 3701-3706, 1986, (cited By 430). @article{Hynes19863701, title = {Outer-Sphere Electron-Transfer Reactions and Frequency-Dependent Friction}, author = {J T Hynes}, doi = {10.1021/j100407a044}, year = {1986}, date = {1986-01-01}, journal = {Journal of Physical Chemistry}, volume = {90}, number = {16}, pages = {3701-3706}, abstract = {A theory is developed for describing the dynamical influence of slow non-Debye polar solvent relaxation dynamics on electron-transfer rates. This relaxation is formulated in terms of the frequency-dependent friction acting on the reaction coordinate. Its influence on the rate is examined in three important and distinct regimes of reaction adiabaticity, and illustrative calculations for a simple two relaxation time model of n-propyl alcohol solvent are presented. An implication of the theory is that slow collective hydrogen bonding dynamics in alcoholic solvents need not dominate the solvent influence on activated electron-transfer rates. textcopyright 1986 American Chemical Society.}, note = {cited By 430}, keywords = {}, pubstate = {published}, tppubtype = {article} } A theory is developed for describing the dynamical influence of slow non-Debye polar solvent relaxation dynamics on electron-transfer rates. This relaxation is formulated in terms of the frequency-dependent friction acting on the reaction coordinate. Its influence on the rate is examined in three important and distinct regimes of reaction adiabaticity, and illustrative calculations for a simple two relaxation time model of n-propyl alcohol solvent are presented. An implication of the theory is that slow collective hydrogen bonding dynamics in alcoholic solvents need not dominate the solvent influence on activated electron-transfer rates. textcopyright 1986 American Chemical Society. |
Chemical Reaction Rates and Solvent Friction Article de journal J T Hynes Journal of Statistical Physics, 42 (1-2), p. 149-168, 1986, (cited By 86). @article{Hynes1986149, title = {Chemical Reaction Rates and Solvent Friction}, author = {J T Hynes}, doi = {10.1007/BF01010844}, year = {1986}, date = {1986-01-01}, journal = {Journal of Statistical Physics}, volume = {42}, number = {1-2}, pages = {149-168}, abstract = {The role of the dynamic solvent friction in influencing the rates of chemical reactions in solution is described. Features considered include (a) the bias of the reaction coordinate toward a direction of lesser friction in the diffusive limit, (b) the importance of frequency-dependent friction in atom transfers, tunneling reactions and isomerizations, (c) the dynamic nonequilibrium solvation in charge transfers which leads to a polar solvent molecule reorientation time dependence for the rate, and (d)the importance of internal degrees of freedom in the location of the Kramers turnover for isomerizations. textcopyright 1986 Plenum Publishing Corporation.}, note = {cited By 86}, keywords = {}, pubstate = {published}, tppubtype = {article} } The role of the dynamic solvent friction in influencing the rates of chemical reactions in solution is described. Features considered include (a) the bias of the reaction coordinate toward a direction of lesser friction in the diffusive limit, (b) the importance of frequency-dependent friction in atom transfers, tunneling reactions and isomerizations, (c) the dynamic nonequilibrium solvation in charge transfers which leads to a polar solvent molecule reorientation time dependence for the rate, and (d)the importance of internal degrees of freedom in the location of the Kramers turnover for isomerizations. textcopyright 1986 Plenum Publishing Corporation. |
Intramolecular Energy Transfer in Simple Model Organometallics Article de journal T Uzer; J T Hynes Journal of Physical Chemistry, 90 (16), p. 3524-3527, 1986, (cited By 24). @article{Uzer19863524, title = {Intramolecular Energy Transfer in Simple Model Organometallics}, author = {T Uzer and J T Hynes}, doi = {10.1021/j100407a014}, year = {1986}, date = {1986-01-01}, journal = {Journal of Physical Chemistry}, volume = {90}, number = {16}, pages = {3524-3527}, abstract = {Classical trajectory calculations and analysis of intramolecular energy flow in model organometallic compounds containing an acetylenic linkage are presented. For symmetric models M-C$equiv$C-M, the rigid acetylenic linkage fails to act as an energy blocker due to weak anharmonic detuning of the flanking carbon - metal bond frequencies. In certain asymmetric models M-C$equiv$C-X, however, energy localization in an excited M-C bond can be maintained in the presence of anharmonicity. textcopyright 1986 American Chemical Society.}, note = {cited By 24}, keywords = {}, pubstate = {published}, tppubtype = {article} } Classical trajectory calculations and analysis of intramolecular energy flow in model organometallic compounds containing an acetylenic linkage are presented. For symmetric models M-C$equiv$C-M, the rigid acetylenic linkage fails to act as an energy blocker due to weak anharmonic detuning of the flanking carbon - metal bond frequencies. In certain asymmetric models M-C$equiv$C-X, however, energy localization in an excited M-C bond can be maintained in the presence of anharmonicity. textcopyright 1986 American Chemical Society. |
Transition-State Solvent Effects on Atom Transfer Rates in Solution Article de journal B M Ladanyi; J T Hynes Journal of the American Chemical Society, 108 (4), p. 585-593, 1986, (cited By 30). @article{Ladanyi1986585, title = {Transition-State Solvent Effects on Atom Transfer Rates in Solution}, author = {B M Ladanyi and J T Hynes}, doi = {10.1021/ja00264a005}, year = {1986}, date = {1986-01-01}, journal = {Journal of the American Chemical Society}, volume = {108}, number = {4}, pages = {585-593}, abstract = {The static ``caging'' effect of an inert solvent on the rates of atom-transfer reactions is studied theoretically. In addition to their intrinsic interest, these effects are important in isolating the solvent ``dynamic'' influence on solution rates. Calculated variational transition-state theory rates for the model H exchange reaction between methyl radical and methane are compared in the gas phase and in model compressed Ar and Xe solvents over a wide pressure range. The calculated solvent enhancement of the rate varies with solvent, pressure, and reaction system and can reach up to several orders of magnitude. Calculated activation volumes vary strongly with pressure and bear little relation to values calculated solely in terms of geometric changes on passage to the transition state. The solvent rate enhancement is found to be much less for simple geometric isomerizations. But it is pointed out that the observed variation of the volume of activation with pressure can play an important role in the interpretation of experimental rates in terms of dynamic solvent effects. textcopyright 1986, American Chemical Society. All rights reserved.}, note = {cited By 30}, keywords = {}, pubstate = {published}, tppubtype = {article} } The static ``caging'' effect of an inert solvent on the rates of atom-transfer reactions is studied theoretically. In addition to their intrinsic interest, these effects are important in isolating the solvent ``dynamic'' influence on solution rates. Calculated variational transition-state theory rates for the model H exchange reaction between methyl radical and methane are compared in the gas phase and in model compressed Ar and Xe solvents over a wide pressure range. The calculated solvent enhancement of the rate varies with solvent, pressure, and reaction system and can reach up to several orders of magnitude. Calculated activation volumes vary strongly with pressure and bear little relation to values calculated solely in terms of geometric changes on passage to the transition state. The solvent rate enhancement is found to be much less for simple geometric isomerizations. But it is pointed out that the observed variation of the volume of activation with pressure can play an important role in the interpretation of experimental rates in terms of dynamic solvent effects. textcopyright 1986, American Chemical Society. All rights reserved. |