Low-energy electron collisions with O2: Test of the molecular R-matrix method without diagonalization
Michal Tarana and Chris H. Greene
Accepted
Electron collisions with at scattering energies below 1 eV are studied in the fixed-nuclei approximation for a range of internuclear separations using the molecular method. The scattering eigenphases and quantum defects are calculated. The parameters of the resonance and the energy of the bound negative ion are then extracted. Different models of the target that employ molecular orbitals calculated for the neutral target are compared with models based on anionic orbitals. A model using a basis of anionic molecular orbitals yields physically correct results in good agreement with experiment. An alternative method of calculation of the is tested, where instead of performing a single complete diagonalization of the Hamiltonian matrix in the inner region, the system of linear equations is solved individually for every scattering energy. This approach is designed to handle problems where diagonalization of an extremely large Hamiltonian is numerically too demanding.