Analysis of molecular shape changes along reaction paths

Abstract

AbstractIn this work, a detailed discussion and illustrative example are given for a new conceptual approach to the notion of similarity between nuclear configurations. We analyze the changes in molecular shape, as described by a topological characterization of molecular envelope surfaces, along reaction paths. This approach provides an independent definition of formal species along the path, defined in terms of molecular shape, rather than based on the curvature properties of the potential energy function. The two approaches are compared in this work, using the [1,3] hydrogen‐shift in formic acid as an illustrative example. The reaction is studied at SCF and MP2 ab initio levels. Although the actual reaction paths are different, the molecular shape changes encountered along them are similar, indicating that the essential shape changes provide chemical information on a more fundamental level than do detailed reaction paths.