Locating minima on seams of intersecting potential energy surfaces. An application to transition structure modeling

Abstract

It is proposed that the equivalent of a transition structure within a force field model can be defined as the lowest energy structure on the seam of the two intersecting potential energy surfaces valid for the reactant and product. The present paper describes a method for locating such minima and compares the obtained results with ab initio transition structures and with experimental activation energies for closely related systems. Using Allinger's MM2 force field, it is shown that the method generates transition structures with overall features close to those obtained by ab initio calculations, and Yends in activation energies are also reproduced reasonably well