Chapter 10 - Finding minima, transition states, and following reaction pathways on ab initio potential energy surfaces

Abstract

This chapter discusses recent advancements and commonly used techniques for exploring potential energy surfaces (PESs) are surveyed in the context of electronic structure methods. Specifically, minimization, transition state optimization, and reaction path following are discussed. In addition to reviewing current progress in these areas, the chapter also deals with a number of practical discussions regarding minimization, transition state optimization, and reaction path following, including suggestions for overcoming common pitfalls. PESs play a central role in computational chemistry. It forms a central concept in the theoretical description of molecular structures, properties, and reactivities. The study of most chemical processes and properties by computational chemists begins with the optimization of one or more structures to find minima on PESs, which correspond to equilibrium geometries. To obtain reaction barriers and calculate reaction rates using transition state theory (TST), it is necessary to locate the first-order saddle points on the PES, which correspond to transition states (TS). Often one needs to confirm that a TS lies on a pathway that actually connects the minima corresponding to reactants and products