ELECTRON-IMPACT EXCITATION OF COMPLEX ATOMS AND IONS IV - FORBIDDEN TRANSITIONS IN NI4+

Collision strengths and effective collision strengths for electron-imp act excitation of forbidden transitions between all 16 terms of the gr ound-state configuration 3p(6)3d(6) of Ni4+ have been calculated using the R-matrix method. The importance of including configuration-intera ction wavefunctions both in the target-state expansion and in the (N 1)-electron quadratically integrable function expansion is discussed. The effect of the inclusion of 3p(6)3d(5)4s states has also been inve stigated. Although the collision strengths were significantly altered due to resonances in both of these studies, the resulting change in th e effective collision strength was small. Collision strengths were cal culated for incident electron energies from threshold to 16 Ryd and ta bles of effective collision strengths are presented for electron tempe ratures in the range from 10(3) K to 5 x 10(5) K.