Electron collisions with an ozone molecule using the R-matrix method

Abstract

Elastic integral, differential and momentum transfer cross sections for electron collisions with an O3 molecule have been calculated in a 16-state R-matrix approach. The 16 target states have symmetries X1A1, 13B2, 13B1, 13A2, 11B1, 11A2, 23B2, 21A1, 11B2, 23A2, 21A2, 23B1, 21B2, 21B1, 31A1 and 13A1 and have been represented by configuration interaction (CI) wavefunctions. In our CI model, we keep the core 6 electrons frozen in doubly occupied molecular orbitals 1a1, 2a1 and 1b2. The complete active space consists of 18 valence electrons that are allowed to move freely among 12 molecular orbitals: 3a1, 4a1, 5a1, 6a1, 7a1, 1b1, 2b1, 2b2, 3b2, 4b2, 5b2 and 1a2. This CI model gave an adequate description of the vertical spectrum of these excited states which span the energy range 0–10 eV and also gave a good representation of the charge cloud of the ground state at its equilibrium geometry which provided a dipole moment of 0.61 D in good accord with the experimental value 0.53 D. Our calculations detect one bound O−3 state (2B1) at the equilibrium geometry of the O3 molecule. We also find two broad shape resonances in 2A1 and 2B2 symmetries out of which the 2A1 resonance supports dissociative electron attachment when an O–O bond is stretched beyond 3.1 a0. Born correction is applied for the elastic and the dipole allowed transitions to account for partial waves higher than l = 4 that are excluded in the R-matrix calculation. Elastic and excitation cross sections are presented for incident electron energies up to 15 eV and our results are compared with the other theoretical and experimental works.