High-lying doubly excited states of H-and He

Abstract
For the high-lying doubly excited states of H- and He, the authors have quantitatively examined diabaticity at close avoided crossings between two hyperspherical adiabatic potentials and have confirmed that the close avoided crossings in the diagrams of the adiabatic potential curves can be reconnected 'diabatically' for the N manifolds investigated here. Using these diabatically connected hyperspherical potentials, they have calculated the energy levels of the high-lying doubly excited states, i.e. 1Se states from N=7-9 hydrogenic thresholds for H-, as well as those of 1Se states with N=6 and 7, and of 1P0 and 1De states with N<or=4 for He. Their results agree reasonably with other elaborate calculations based on the complex coordinate rotation method within a few percent accuracy.