Abstract

The reaction force F(R) and the reaction force constant κ(R) are intrinsic and universal properties of any process that can be represented by a potential energy profile V(R), where R is a reaction coordinate. F(R) is the negative gradient of V(R) along R; κ(R) is the second derivative of V(R). The minima and maxima of F(R), which correspond to the zeroes of κ(R), define stages of a process. Some of these are dominated by structural effects within the reacting system, while others are transitions to new species. In a transition stage, the focus is upon that entire region of the reaction coordinate, not upon a single point, a transition state. It is shown that activation energies have two components. Awareness of these can help in understanding reaction mechanisms as well as the roles played by solvents or catalysts. F(R) and κ(R) depend solely upon the V(R) of a process and provide insight into its nature and energetics.