Minimum energy path reaction rate theory

The Canonical Variational Theory [39] is an extension of the Transition State Theory (TST) [40,41]. This theory minimizes the errors due to recrossing trajectories [42-44] by moving the dividing surface along the minimum energy path (MEP) so as to minimize the rate. The reaction coordinate (s) is defined as the distance... 

The progress of a chemical reaction comprises variation of the positions of the atomic nuclei along a multidimensional potential hyperface. The path with minimum energy with respect to the other degrees of freedom is called the reaction coordinate. If the potential along this coordinate exhibits a maximum, it is called the transition state and its difference to the initial state is denoted as activation energy E. From the partition functions of the initial and transition states, the activation entropy AS is derived. Within the framework of transition state theory (TST) [1], the rate constant for the reaction is then given by... 

In this Section we discuss and compare the results obtained using the various theories of Section 3, and a variational transition state theory with a tunnelling correction [9]. The reaction we concentrate on is H+BrH - HBr+H. We emphasize the rate constants, but also discuss reaction cross sections. The potential energy surface we used in the H+BrH computations is of a semiempirical diatomics in molecules type, the form of which (called DIM-3C) is due to Last and Baer [ll]. The surface contains a three-centre integral term that has been parameter-ised [33] by comparing ESA-CSA calculations with an experimental [3] room temperature rate constant for the D+BrH -) DBr+H reaction. The minimum potential energy path is collinear, and there is a strong... 

---