Chemical Physics Letters, Vol.723, 82-88, 2019
The low-lying adiabatic states of the K-2(+) alkali dimer
Despite the simplicity of the K-2(+) alkali dimer with a single active electron, comparison of the ab initio results of Berriche et al. (2008) with those of Magnier and Frecon (2003) based on a model potential approach reveals a number of serious disagreement concerning several excited states. In particular, the 5(2)Sigma(+)(u), 6(2)Sigma(+)(g), 6(2)Sigma(+)(u), 7(2)Sigma(+)(g),7(2)Sigma(+)(u), 3(2)Pi(g), 4(2)Pi(g) and 2(2)Delta(u) states which are found to be repulsive by Magnier and Frecon, but attractive when ab initio techniques are employed. To clarify the origin of this disagreement, the adiabatic energies and spectroscopic constants are re-computed for the low-lying states of the K-2(+) alkali dimer within a model potential framework. Contrary to the claims of Magnier and Frecon, the new results based on a model potential approach agree well with the ab initio ones.