Electron-impact excitation of O iii in the distorted-wave approximation

The ³P→¹D electron-impact excitation cross section within the ground configuration of doubly ionized oxygen is calculated in the distorted-wave approximation. An essential element of the present treatment is that we do not assume orthogonality between core and scattering orbitals of the same angular symmetry. Resonance structures are included through the use of quantum defect theory. Near threshold the effect of an isolated autoionization resonance in the dominant ²Dᵒ partial wave is found to be important, in agreement with previous close-coupling results.