The Many-Body Expansion in Chemistry

The Many-Body Expansion (MBE) of the energy of a chemical system is a powerful tool that encodes physical descriptors of cooperative effects in chemical systems. Depending on the definition of what a “body” is, the expansion can be applied to a wide variety of chemical ensembles. When applied to hydrogen bonded systems, such as water and aqueous ionic clusters including ions in the Hofmeister series, it has direct implications in the development of many-body, non-additive interaction potentials and can be used to drive MBE-based molecular dynamics to study condensed phase aqueous environments. Its extension to allow the “break-up” of molecules offers insight into the origin of the alleged “first-row anomaly” in simple molecules, whereas work in progress for its application to metals can provide insights into the energetic stabilization of periodic ensembles and surface active sites that are important in chemical transformations.