COVALENT BOND ORDERS IN THE TOPOLOGICAL THEORY OF ATOMS IN MOLECULES

A new definition of covalent bond orders, based on partitioning of the number of electrons within the topological theory of atoms in molecules, is proposed. Unlike the previously proposed definitions, it requires neither references to the basis sets used in the expansion of the molecular wave function nor a parameterization involving a set of standard bonds. For some conjugated molecules, the present approach affords bond orders pertinent to all relevant Lewis (resonance) structures. The new definition, which is tested on a set of several organic molecules, provides bond orders that can serve as molecular indices complementary to Badar atomic charges.