Hypergeometric resummation approach to dissociation and Stark effect in non-rigid dipolar molecules

In a strong electric field, a dipolar molecule will contract or expand and, in extreme cases, dissociate. Considering a two-atomic non-rigid dipole described by the realistic Kratzer model, we compute analytical energy corrections up to fourth order in the field strength for general states and ninth order for the ground state. The fourth-order series is subsequently 'resummed' using the hypergeometric approach (Mera et al 2015 Phys. Rev. Lett. 115 143001). We benchmark the approach against numerical complex scaling results and demonstrate that the resummed series is highly accurate in a wide range of field strengths and, importantly, correctly reproduces the dissociation rate. Finally, Stark shift and dissociation rate are calculated for LiH⁺ as a practical application of the theory. (paper)