Quantum Theory of Atoms in Molecules–Dalton Revisited

This chapter deals with the quantum mechanical definition of the average properties of an atom. It is demonstrated that the topological property that defines the atom determines the definition of its average properties. It reviews only the basic topological properties of a charge distribution in this chapter. Their role in the definition of molecular structure and its change has been recently reviewed in detail. A bound atom is an example of an open quantum system. A quantum description of subsystems must be developed, free to exchange charge and momentum with their environment across boundaries that are defined in real space and that in general change with time. The chapter also reviews that the quantum mechanics has been shown to account for the properties of isolated atoms and for the total properties of a molecular system. The increased understanding that would result from the discovery of a firm theoretical basis for Dalton's theory has not been obtained because of a lack of a quantum definition of an atom in a molecule.