Simple Three-Parameter Model Potential for Diatomic Systems: From Weakly and Strongly Bound Molecules to Metastable Molecular Ions

Based on a simplest molecular-orbital theory of H₂⁺, a three-parameter model potential function is proposed to describe ground-state diatomic systems with closed-shell and/or S-type valence-shell constituents over a significantly wide range of internuclear distances. More than 200 weakly and strongly bound diatomics have been studied, including neutral and singly charged diatomics (e.g., H₂, Li₂, LiH, Cd₂, Na₂⁺, and RbH^-), long-range bound diatomics (e.g., NaAr, CdNe, He₂, CaHe, SrHe, and BaHe), metastable molecular dications (e.g., BeH⁺⁺, AlH⁺⁺, Mg₂⁺⁺, and LiBa⁺⁺), and molecular trications (e.g., YHe⁺⁺⁺ and ScHe⁺⁺⁺).