Electron-impact study of SiN using the R-matrix method

Abstract

We have carried out a comprehensive study of electron-impact on an open-shell SiN molecule by using the R-matrix method. Elastic (integrated and differential), momentum-transfer, excitation and ionization cross sections, along with efffective collision frequencies over a wide electron temperature range (100–100 000 K) have been presented. The target states are represented by including correlations via a configuration interaction formalism. The results of the static-exchange, one-state and 28-state close-coupling approximation are presented. Our study has detected a shape resonance, two core-excited and three Feshbach resonances in the 28-state model. All calculations are done in C 2v point group. We detect a stable bound state of SiN− of 1 A 1 symmetry having configuration ...7σ 2, 1π 4,2π 4 with a Vertical Electronic Affinity value of 2.86 eV which is in good agreement with the experimental (adiabatic) value of 2.949 ± 0.008 eV. The ionization cross sections are calculated using the Binary-Encounter-Bethe (BEB) Model in which molecular orbitals at self-consistent Hartree-Fock (HF) level are used to calculate kinetic and binding energies of the occupied molecular orbitals. For scattering calculations we have used partial waves up to l = 4 to represent continuum electron in our R-matrix approach. A Born top-up procedure is invoked for dipole-allowed transitions to account for the contribution of partial waves higher than l = 4 to obtain converged cross-sections.