Doubly excited autoionizing states of H2 above the second ionization threshold: the Q2 resonance series

Abstract

We report extensive calculations of energy positions, autoionization widths and branching ratios for the Q2 doubly excited states of H2 lying above the second ionization threshold 2Σu+. We present results for 60 doubly excited states of the 1,3Σg,u+, 1,3Πg,u, and 1,3Δg,u symmetries in the range of internuclear distances 0⩽R⩽6 a.u. The resonance parameters have been obtained using the Feshbach theory and an L2 representation of the nonresonant continuum with B-spline functions. Our results are compared with previous theoretical data. We have found significant discrepancies for states of the 1Σg+ and 1Σu+ symmetries.