Electron impact excitation of semi-forbidden transitions in O III

Calculates the collision strengths for the transitions 1s 2 2s 2 2p 23 P e to 1s 2 2s2p 35 S 0 , 1s 2 2s2p 35 S 0 to 1s 2 2s2p 33 D 0 and 1s 2 2s2p 35 S 0 to 1s 2 2s2p 33 P 0 in O III using the R-matrix method. The transition 3 P e to 5 S 0 is of particular importance in diagnostic studies of densities in the quiet sun and in coronal holes. The authors include all channels with configurations 1s 2 2s 2 2p 2 , 1s 2 2s2p and 1s 2 2p 4 in the expansion of the total wavefunction. They also include 3s, 3p and 3d pseudo-orbitals and allow for configuration interaction in all the included states, plus the correlation terms in the total wavefunction. Results are presented for collision strength and its average over a Maxwellian distribution over a wide temperature range and are compared with other work.