On the topological approach to the concept of chemical structure

In this article we propose a new topology, based on the stable attractors of the gradient field of the potential energy hypersurface, that may be used as a general definition of a stable chemical structure. We further construct two examples of particular realizations of this abstract topology. One of them is closely related to the catchment–region topology of Mezey and the other one to the molecular–graph model of Bader. A particularly interesting point is that both topologies lead to equivalent definitions of molecular structure; in particular, they permit us to differentiate between cis-trans isomers and rotational conformers, that had equivalent structures in the definition proposed by Bader.