Group-Theoretic Approach to Two-Electron Correlations in Atoms

Abstract

We suggest that group-theoretic techniques may be useful for studying two-electron correlations in atoms. We show that matrix elements of the Coulomb interaction for doubly excited states of the ${}_{}{}^1{}_{}{}^{}S$ configuration can be approximated by a constant plus a pairing term. The latter gives rise to a highly correlated state similar to a Cooper pair in the electron gas. It may be identified with the state that leads to the Wannier threshold law for the escape of two electrons from a Coulomb core.