Undulating potential curves of the Rydberg states of NaHe

The Rydberg states of alkali/rare-gas diatomic molecules show complex potential energy curves due to two effects: (1) avoided crossings between two close atomic configurations, and (2) undulations originating from the atomic orbital structures of the alkali Rydberg states. This work reports the potential energy curves for ten 2Σ+ states correlated to the atomic states from Na(3s) to Na(6s) obtained from accurate ab initio calculations. We give the spectroscopic constants and present a complete analysis for these potential curves.