Oscillator Strengths and Electron Collision Rates for Fine-Structure Transitions in O II

Electron impact excitation collision strengths for the fine-structure transitions between the lowest 13 levels of the 2s²2p³, 2s2p⁴, and 2s²2p²3s configurations and from these levels to the next 22 other lowest levels of the 2s2p⁴, 2s²2p²3s, and 2s²2p²3p configurations have been calculated using a 62-level Breit-Pauli R-matrix approach with orthogonal radial functions and a 47-level Breit-Pauli R-matrix approach with nonorthogonal radial functions. A B-spline basis has been used for the description of continuum functions, and no orthogonality constraint has been imposed between the continuum functions and the valence atomic orbitals in 47-level calculation. Oscillator strengths and transition probabilities for the fine-structure transitions have been calculated using nonorthogonal orbitals in the multiconfiguration Hartree-Fock approach. The present oscillator strengths normally compare very well with a previously available calculation. The collision strength is averaged over a Maxwellian velocity distribution to obtain the effective collision strengths as a function of electron temperature. The effective collision strengths are presented over a wide temperature range (2 × 10³ to 10⁵ K) suitable for modeling of astrophysical plasmas.