General complex rotated finite-element method for predissociation studies of diatomic molecules: An application on the (1–6)¹Σ_g⁺ states of H₂

An exterior complex rotated finite element method was applied on the diabatic multichannel Schrödinger equation in order to compute and compare rovibronic energy structures, predissociation widths, and nonradiative lifetimes for levels in the (1–4), (1–5), and (1–6)¹Σ_g⁺ manifolds of H₂. The rotationless (v,J=0) levels are found to be more or less shifted relative to each other when comparing the results for these three manifolds. The existence of homogeneous spectroscopic perturbations was investigated by studying the rovibronic (v,J=0−10) sequences for energies and level widths. Known experimental and theoretical radiative lifetimes were used to estimate present levels that might be spectroscopically measurable. The computed level widths for the EF, GK, and H electronic levels were generally found to be about two orders of magnitude larger than previously reported [ P. Quadrelli, K. Pressler, and L. Woiniewicz J. Chem. Phys. 93 4958 (1990)], indicating a somewhat stronger predissociation.