Abstract

Simplified group function (SGF) theory is used to analyse the energetic contributions to the interatomic potentials of the diatomics H₂⁺, H₂, He₂⁺ and He₂. These species, which contain one, two, three and four electrons respectively, range from the strongly (H₂) to the weakly (He₂) bonded chemical entities. SGF theory provides a simple conceptual model of the processes occurring during chemical bonding, and the results obtained in this work may be generalized so as to explain the bonding in larger, more complex systems. The relative merits of the perturbational and variational approaches and of the Lowdin and Gram-Schmidt orthogonalization procedures are discussed.