Electron collisions with OClO using the R-matrix method

The R-matrix method is used to calculate elastic and excitation cross sections of four low-lying electronic states of the OClO molecule, designated as the X ²B₁, 1 ²A₁, 1 ²B₂ and 1 ²A₂ states. Eight states, four doublets and four quartets are included in the close-coupled expansion; these excited states are predicted to have vertical excitation energies in the range 2.956-8.206 eV, in fair agreement with published multireference configuration-interaction calculations. The experimentally determined excitation energy of the atmospherically most important state 1 ²A₂ centred around 3.5 eV is in excellent agreement with our value of 3.44 eV. A bound state of OClO^- with ¹A₁ symmetry with an adiabatic electron affinity of 1.558 eV at equilibrium geometry of OClO is found. There is a shape resonance of ³B₁ symmetry at 2.96 eV and higher-lying shape resonances of ¹B₁, ¹A₂ and ³A₂ symmetries located at 5.75, 8.06 and 7.22 eV, respectively. All the resonances are rather broad. The resonance positions correlate well with the maxima found in dissociative electron attachment cross section measurements. Rotationally inelastic scattering cross sections are compared with experiment and there is very good agreement for electron energies above 100 meV. Excitation cross sections for three excited states are presented for electron-impact energies up to 10 eV. Total integral cross sections are also compared with experiment.