The electronic structure and spectra of the <i>X</i> 1Σ+<i>g</i> and <i>A</i> 1Σ+<i>u</i> 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 De (X 1Σ+g) =8297 cm−1 and De (A 1Σ+u) =9299 cm−1; a semiempirical scaling which reproduces the experimental vibrational energy level spacings suggests ’’most-likely’’ dissociation energies De′ (X 1Σ+g=8450±100 cm−1 and De′ (A (1Σ+u) =9400±100 cm−1.