Ab initio study of the alkali-dimer cation Li2+

The potential energy curves and the spectroscopic constants of the electronic states of 2Σg,u+, 2Πg,u and 2Δg,u symmetries of Li2+ ionic system dissociating into Li (2s, 2p, 3s, 3p, 3d, 4s and 4p) + Li+, have been calculated using an ab initio approach. A non-empirical pseudo potential for the Li (1s2) core has been involved and a core-core and core-valence correlation have been added. A good agreement has been obtained for the ground and the first excited states with the available theoretical and experimental works. However, a clear disagreement between this study and the model potential work of [S. Magnier, S. Rousseau, A.R. Allouche, G. Hadinger, M. Aubert-Frécon, Chem. Phys. 246 (1999) 57] has been observed for several excited states. They found that the 6-7 2Σg+, 3-4, 6 2Σu+, 2 2Πg, 4 2Πu and 1 2Δu states are repulsive, although they are attractive with potential well depths of 10, 100 and 1000 cm−1 in our study.