Autoionization rates for selected double-Rydberg states of barium

We have performed ab initio calculations of several autoionizing double-Rydberg states of Ba. We have also investigated the effects due to electron configuration mixing. These calculations are based on the Hartree-Fock atomic model. Numerical results are presented and are compared with the experimental data for msn's and msn'd states. Although our calculated quantum-defect values are in excellent agreement with experimental values, they do not yield the same dependence of the scaled autoionization rates on the core principal quantum number as deduced from experiment.