DESCRIPTION OF CHEMICAL-REACTIONS IN TERMS OF THE PROPERTIES OF THE ELECTRON-DENSITY

Chemical reactions can be described by utilizing the topological features of the electron density distribution rho(r). This implies defining atoms in molecules, chemical bonds, molecular graphs, molecular structure, structural stability, and changes in molecular structure from a topological point of view. Looked at in this way, chemical reactions are transitions from one structural region to another passing through one or several unstable structures, which can be associated with the transition state(s) of chemical reactions. An alternative way of describing chemical reactions is given by the analysis of the Laplace concentration - nabla2-rho(r). This leads to a more qualitative account of changes in molecular structure owing to chemical reactions. It also has the advantage of briding the gap between molecular-orbital-based and rho(r)-based descriptions of chemical reactions and molecular activity.