The electronic structure and spectra of the X 1Σ+g and A 1Σ+u states of Li2

Abstract

The potential energy curves for the X ¹Σ⁺_g and the A ¹Σ⁺_u states of Li₂ have been calculated on the single configuration Hartree–Fock–Roothaan (HF) level, and on the multiconfiguration self‐consistent‐field (MCSCF) level. The MCSCF results give binding energies D_e (X ¹Σ⁺_g) =8297 cm⁻¹ and D_e (A ¹Σ⁺_u) =9299 cm⁻¹; a semiempirical scaling which reproduces the experimental vibrational energy level spacings suggests ’’most‐likely’’ dissociation energies D_e^′ (X ¹Σ⁺_g=8450±100 cm⁻¹ and D_e^′ (A (¹Σ⁺_u) =9400±100 cm⁻¹.