Rotor-like spectra for some doubly excited two-electron states

Abstract

The authors consider whether strongly correlated electron motion in doubly excited two-electron atoms can be described as collective rotational behaviour similar to that known in nuclear-shell theory. Using computed angular distributions, the authors select group theoretically defined sequences of states which might show quasi-rigid rotational behaviour. Computed levels for these states reveal rotor-like spectra cut off above a certain value of the angular momentum, similar to the cut-off rotor spectra of nuclei. The authors present a simple model for the rotor, and interpret deviations from exact rotor behaviour as a function of shell number, nuclear charge, and angular momentum.