Interatomic exchange energy components

Abstract

AbstractThe diatomic energy components obtained in the framework of the recent chemical energy component analysis can be further decomposed into terms of different physical origins, reflecting electrostatic, exchange, overlap, etc., effects. The proper definition of the interatomic exchange energy component represented a nontrivial task, however. Here, we considered two possible definitions of that quantity. The first is introduced following the definition of the intermolecular exchange. This seemingly straightforward analogy has been found misleading—it leads to a quantity that vanishes in the limit of an NDO‐type integral approximation. The correct definition has been found by analyzing the exchange energy components connected with the delocalized bonding orbitals in a diatomics and generalizing the interatomic exchange energy contribution obtained in this simplest case by the analogy to the respective Coulomb energy component. This definition is adequate for all types of theories, has the correct asymptotic behavior, and exhibits the expected connections with the bond order indices. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003