Electron collisions with the SF2radical using theR-matrix method

We present the elastic and the excitation cross sections of the four lowest-lying electronically excited states of the radical SF 2 using the R -matrix method. These excited states have symmetries 1 3 A 2 , 1 1 A 2 , 1 3 B 1 and 1 1 B 1 . Their vertical excitation energies from the equilibrium geometry of the ground state X 1 A 1 lie in the range 3.40–6.47 eV. Configuration interaction (CI) wavefunctions are used to represent the target states. In our CI model, we keep the core 14 electrons frozen in doubly occupied molecular orbitals 1a 1 , 2a 1 , 3a 1 , 4a 1 , 1b 1 , 1b 2 and 2b 2 . The complete active space consists of 20 valence electrons that are allowed to move freely among the 12 molecular orbitals: 5a 1 , 6a 1 , 7a 1 , 8a 1 , 9a 1 , 2b 1 , 3b 1 , 3b 2 , 4b 2 , 5b 2 , 6b 2 and 1a 2 . Our calculations do not detect any bound SF − 2 states at the equilibrium geometry of the SF 2 molecule. We find two shape resonances of 2 B 2 and 2 A 1 symmetries with their resonance positions at 1.98 eV and 3.36 eV respectively. Their corresponding resonance widths are 1.52 eV and 2.4 eV. Born correction is applied for the elastic and the dipole allowed transitions to account for higher partial waves excluded in the R -matrix calculation. Total cross sections are presented for incident electron energies up to 15 eV. Calculations with asymmetric stretch of SF 2 reveal that 2 B 2 ( 2 A' in C s ) resonance becomes bound at a bond length beyond 3.9 a 0 . We have also determined the equilibrium geometries, the single bond dissociation energies and the vertical detachment energies of the anionic states. The vertical and adiabatic electron affinity of SF 2 are also determined and compared with other works.