Breit‐Pauli R ‐Matrix Calculation for Electron Collision Rates in O iv

Abstract

Electron collision excitation strengths and rates for infrared and ultraviolet lines arising from transitions between the fine-structure levels of the 2s22p, 2s2p2, 2p3, 2s23s, 2s23p, 2s23d, 2s2p3s, 2s2p3p, 2s2p3d, 2s24s, and 2s24p configurations of O IV have been calculated using Breit-Pauli R-matrix approach. Configuration-interaction wave functions have been used for an accurate representation of target levels. These wave functions give excitation energies that are in close agreement with experiment. Oscillator strengths and transition probabilities for UV and EUV lines compare very well with previous calculations. The Rydberg series of resonances converging to the excited levels are explicitly included in the scattering calculation and are found to make substantial contribution to collision strengths. The effective collision strengths are obtained by integrating total collision strengths over a Maxwellian distribution of electron energies, and these are presented over a wide temperature range suitable for modeling of astrophysical plasmas. Significant qualitative and quantitative differences with earlier results of effective collision strengths are noted.