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** Reaction rates transition state **

** Transition state theory reaction **

** Transition state theory reaction rate **

Kinetic theory and transition-state theory try to calculate the rates of chemical reactions starting from a model of molecular interactions. A less ambitious task is to correlate reaction rates with phenomenological laws of various macroscopic processes which have been established experimentally. This type of theory can be termed a phenomenological theory of reaction rates. For the purpose of calculating theoretical reaction rates, chemical reactions are divided into three categories bimolecular associations, uni-molecular dissociations, and intramolecular transformations. [Pg.62]

Theoretical studies of the microsolvation effect on SN2 reactions have also been reported by our coworkers and ourselves (Gonzalez-Lafont et al. 1991 Truhlar et al. 1992 Tucker and Truhlar 1990 Zhao et al. 1991b, 1992). Two approaches were used for interfacing electronic structure calculations with variational transitional state theory (VST) and tunneling calculations. We analyzed both the detailed dynamics of microsolvation and also its macroscopic consequences (rate coefficient values and kinetic isotope effects and their temperature [Pg.25]

Part IV again is a theoretical one, in which different approaches for the calculation of state-specific and thermal rate data are described. The article by A.F. Wagner presents a new approach to describe the influence of hindered rotations on recombination/dissociation kinetics in the framework of transition state theory. In the papers by D.C. Clary and G. Nyman an approximate quantum mechanical method is described and used to calculate thermal rate coefficients for gas phase reactions of interest in atmospheric chemistry which involve polyatomic molecules. Finally, different approaches to describe vibrational relaxation of diatoms in thermal collisions are discussed by E,E, Nikitin, [Pg.351]

Kinetic treatment based on the theory of complex reactions introduced the necessity to calculate quite many parameters (pre-exponential factors, activation energies of elementary reactions, etc.). Therefore a need to estimate independently the rates and surface coverage called for the application of theoretical approaches, based on thermodynamics and transition state theory, as well as other tools (ultra-high vacuum studies, spectroscopy) to get necessary data and reduce the number of parameters in statistical data fitting. [Pg.107]

The calculation of theoretical rate constants for gas-phase chemical reactions involved in atmospheric chemistry is a subject of great interest. Theoretical kinetic methodologies utilize the quantum chemical characterization of the stationary points along the PES of a reaction to calculate the rate constants and product distributions. These methods allow for the elucidation of rate constants over the temperature and pressure range in the atmosphere. Various theoretical methods are available for rate constant calculations. Here, we focus on transition state theory (TST) and its variants to calculate the reaction rate constants. [Pg.487]

In dilute solutions it is possible to relate the activity coefficients of ionic species to the composition of the solution, its dielectric properties, the temperature, and certain fundamental constants. Theoretical approaches to the development of such relations trace their origins to classic papers by Debye and Huckel (6-8). For detailed treatments of this subject, refer to standard physical chemistry texts or to treatises on electrolyte solutions [e.g., that by Hamed and Owen (9)]. The Debye-Hiickel theory is useless for quantitative calculations in most of the reaction systems encountered in industrial practice because such systems normally employ concentrated solutions. However, it may be used together with transition state theory to predict the qualitative influence of ionic strength on reaction rate constants. [Pg.191]

** Reaction rates transition state **

** Transition state theory reaction **

** Transition state theory reaction rate **

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