Potential-Energy Curves for CO and CO+

Potential-energy curves for the X 1Σ+, A 1Π, I 1Σ−, a 3Π, a′ 3Σ+, d 3Δi, and e 3Σ− electronic states of CO and the X 2Σ+, A 2Πi, and B 2Σ+ electronic states of CO+ have been calculated using a modification of the Rydberg—Klein—Rees method. The curves for the a 3Π, d 3Δi, and A 2Πi states, which are intermediate between Hund's Cases (a) and (b), represent fictitious rotationless states calculated using the true Bv. Benesch and co-workers have shown theoretically that this representation is correct for such intermediate cases. The numerical results for the A 2Πi state presented here confirm their conclusions.