Long-range three-body atom-diatom potential for doublet Li ₃

An accurate long-range ab initio potential energy surface has been calculated for the ground state ^X2A′ lithium trimer in the frozen diatom approximation using all electron RCCSD (T). The ab initio energies are corrected for basis set superposition error and extrapolated to the complete basis limit. Molecular van der Waals dispersion coefficients and three-body dispersion damping terms for the atom-diatomic dissociation limit are presented from a linear least squares fit and shown to be an essentially exact representation of the ab initio surface at long range.