MRD-CI calculations for the vertical electronic spectrum of the hydroperoxyl radical

Abstract

Calculations of the multi-reference double-excitation CI (MRD-CI) variety are reported for the equilibrium geometry of the HO2 radical in order to describe the vertical electronic spectrum of this system up to and including its lowest ionization potentials; an AO basis consisting of 45 cartesian gaussians is thereby employed. The strongest transition in the spectrum is predicted to be the 1a″ → 2a″ π → π* species calculated at 5.90 eV with an f value of 0.065 and this process is assigned to the broad feature observed experimentally with an intensity maximum in the 5.9-6.05 eV spectral region. The lowest-energy HO2 transition is found to correspond to the 7a′ → 2a″ excitation (calc. 0.93 eV, exp. 0.88 eV) while the 6a′ → 2a″ counterpart is calculated at 6.49 eV. The lowest Rydberg-type (3s) states are predicted to lie at 8.0 eV while the corresponding ionic states are found at 11.65 (3A″), 12.34 (1A′) and 12.57 eV (1A″) respectively. © 1978.