Electronic structure with a dipole moment calculation of the low-lying electronic states of the KHe molecule

The KHe molecular system is extensively studied by multi-reference configuration interaction calculations. Potential energy curves are constructed for 20 lowest electronic states, and molecular parameters are extracted. A comparison of our results with previous works shows remarkable agreement. A further calculation of the dipole moment functions through a wide range of the internuclear separation is performed and their corresponding curves are presented. Charge transfer is detected from the change in the sign of these functions particularly for R < R _e. Negative dipole moment values near R _e are predicted for 3 excited states, (1)²Π, (3)²Σ⁺ and (1)⁴Π, which are of a relatively short-range strong-binding nature. On the other hand, weakly binding long-range excited states predict positive values of the dipole moment near R _e reflecting the K^–He⁺ polarity.