Ab initio calculations of low-lying potential energy surfaces of the HHeF system

The low-lying singlet potential energy surfaces for the HHeF system have been calculated using the ab initio electronic structure method at the multireference configuration interaction level of theory. It is found that the interaction of helium with HF(B1Σ+) in the ion-pair electronically excited state is attractive in a wide rage of the orientation angle and that the helium atom strongly stabilize the ion-pair HHe+F− complex on the 31A′ surface, which is asymptotically correlating to the HF(B1Σ+) state. We also found that the electronically nonadiabatic coupling between the 11A′ and 31A′ states plays an essential role in the topographical features of these two surfaces.