23: Barrier Crossing and Activated Processes
- Page ID
- 294373
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The rates of chemical reaction are obtained by calculating the forward flux of reactant molecules passing over the transition state, i.e. the time rate of change of concentration, population, or probability for reactants passing over the transition state.
\[ \langle J^‡_f \rangle = dP^‡_R/dt \] ‡
- 23.1: Transition State Theory
- Transition state theory is an equilibrium formulation of chemical reaction rates that originally comes from classical gas-phase reaction kinetics.
- 23.2: Kramers’ Theory
- In our treatment the motion of the reactant over the transition state was treated as a free transitional degree of freedom. This ballistic or inertial motion is not representative of dynamics in soft matter at room temperature. Kramers’ theory is the leading approach to describe diffusive barrier crossing. It accounts for friction and thermal agitation that reduce the fraction of successful barrier crossings.