Ab initiocalculations of perturbed core-excited resonances in H₂associated with H ,n=3: analogies and differences with doubly-excited helium

Abstract

We have carried out ab initio R-matrix calculations of highly excited diatomic hydrogen (R ¼ 1.4 au, 1 Å u symmetry) in the region near the n ¼ 3 group of thresholds of H þ 2 . Spheroidal coordinates were used and all channels with ' ¼ 0, 1 and 2 associated with the H þ 2 n ¼ 2 and 3 thresholds were included in the calculations. Generalized multichannel quantum defect theory (GMQDT) has been employed to calculate the resulting resonance structures. Strong configuration interaction is predicted to occur between the various ionization and Rydberg channels, producing an irregular pattern of Rydberg resonances characterized by strongly varying electronic autoionization widths. Analogies with doubly excited resonances in He are uncovered despite the lowered symmetry of the molecule as compared to the atom.

Highly excitedΣ−states of molecular hydrogen

“…Our "halfium model" combines the variational eigenchannel R-matrix method [13] with the generalized multichannel quantum defect theory (GMQDT) [14] implemented using prolate spheroidal electron coordinates. The approach has been used to investigate singlet ungerade symmetries ( 1 u , 1 u ) [7,15] and gerade symmetries ( 1 g , 1 g , 1 g ) [16], both for the bound and the continuum (autoionization) regions.…”