On the Electronic Energy of a One-Electron Diatomic Molecule near the United Atom

The behavior of the electronic energy for the ground state of a one-electron heteronuclear diatomic molecule in the vicinity of the united atom is obtained through terms of order R5 in the internuclear distance R. The presence of a term in R5logR reveals that the electronic energy is not an analytic function of R at the united atom. The expansion is checked by means of the Hellmann—Feynman theorem and the work of Dalgarno and Lynn.