Theoretical Approaches to Structural Stability and Shape Stability Along Reaction Paths

Abstract

This chapter reviews recent developments on the analysis of interrelations between configurational rearrangements and changes in potential energy and molecular shape. The notions of structural stability (associated with energy changes) and shape stability (associated with changes in molecular surfaces) are discussed. Procedures used to locate shape transitions (that is, the topological equivalent to geometrical structural transitions) along reaction paths or molecular dynamics trajectories are presented and exemplified for some chemical reactions. The techniques provide a useful insight into the changes in molecular properties along reactions paths, something which is not always apparent when studying the potential energy exclusively. The role of the energy changes in modifying the molecular shape is discussed in detail and we provide quantitative measures of structural similarity for the conformations of flexible molecules.