Transition rates and electron impact excitation rates for O III

Transitions probabilities, electron excitation collision strengths and rate coefficients for a large number of O III lines have been calculated in the close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method is employed for an accurate representation of the target wave functions. The close-coupling expansion contains 202 O III fine-structure levels comprising the 5 levels of the ground configuration 2s$^{\mathrm{2}}$2p$^{\mathrm{2}}$, 10 levels of first excited configuration 2s2p$^{\mathrm{3}}$, 4 levels of the 2p$^{\mathrm{4}}$ configuration, all levels for the 2p excitation to the 2s$^{\mathrm{2}}$2p3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s configurations, and all levels for the 2s excitation to the 2s2p$^{\mathrm{3}}$3s,3p,3d configurations. The collision strengths have been calculated for the 20302 transitions between all 202 fine-structure levels. There is an overall good agreement with the recent R-matrix calculations by Storey et al. (2014) for the transitions between first 5 levels of the ground 2s$^{\mathrm{2}}$2p$^{\mathrm{2}}$ configuration, but significant discrepancies have been found with Palay et al. (2012) for transitions to the 2s$^{\mathrm{2}}$2p$^{\mathrm{2}} \quad^{\mathrm{1}}$S$_{\mathrm{0}}$ level. A fair agreement is found with the LS-coupling calculation of Aggarwal and Keenan (1999) for transitions to the 2s$^{\mathrm{2}}$2pnl states, with average discrepancies of about 30{\%}. However, rate coefficients differ by up to a factor of 10 for some transitions. The present calculations provide data sets that should allow a more detailed treatment of the available measured spectra from different space observatories. [1] P. Storey et al. \quad 2014 MNRAS \textbf{441 }3028 [2] E. Palay et al. \quad 2012 MNRAS \textbf{423 }L35 [3] K. Aggarwal and F. Keenan 1999 ApJS \textbf{123 }311