Validity of the isolated resonance picture forH2autoionizing states

Abstract

The isolated resonance picture (IRP) is tested by comparing calculations on doubly excited autoionizing states of ${\mathrm{H}}_{2}$ by using two different theoretical approaches: a recent implementation of the exterior complex scaling method and the standard Feshbach method with $B$-spline basis sets. These calculations demonstrate that the IRP can yield poor approximations to autoionization widths when doubly excited states approach the ionization threshold at large internuclear distances, $R$. In contrast, at small $R$ where avoided crossings appear, the IRP produces accurate resonance parameters.