Ab initio study of the ground and excited states of LiNe

The intermolecular potentials for the X 2 Σ and A 2 Π states of Li … Ne were studied by a variety of multiconfiguration, single configuration and perturbation methods ( CASPT 2). The A 2 Π excited state was calculated to have a well depth of 214 cm −1 at an internuclear spearation of 2.26 Å ( ACPF ) in excellent agreement with the 224 cm −1 derived from experimental data. A smaller well of 15.8 cm −1 was found for the X 2 Σ ground state at an intermolecular separation of 5.28 Å ( ACPF ). These results are in better agreement with experimental results than the previously reported pseudopotential calculations. The comparison of CI calculations with CASPT 2 results shows that the latter is able to give good results for interacting systems. © 1993 John Wiley & Sons, Inc.