Modern valence-bond description of the ground state of Li2–

Abstract

Ab initio calculations based on spin-coupled (SC) theory are used to investigate the electronic structure of the attractive X ²Σ_u⁺ ground state of the Li₂^– anion, which is stable with respect to detachment of an electron. The single-configuration SC wavefunction dominates a subsequent multi-configuration calculation. The resulting potential-energy curve resembles closely those obtained from elaborate configuration interaction calculations. The SC wavefunction provides a simple, but accurate, description of the correlated electronic motion in this molecule. Topological analysis of the total electron density reveals a non-nuclear attractor at the midpoint.