Electron impact excitation of complex atoms and ions. Pt. 2: forbidden transitions in Ni+

This letter reports the first application of the new R-matrix program package RMATRX II to electron impact excitation of a near neutral open d-shell ion. In this calculation for Ni+, all states corresponding to the configuration 3d9, 3d84s and 3d84p have been included in the expansion of the total wavefunction. Thermally averaged collision strengths for forbidden transitions involving the even parity states are presented in tabular form for temperatures between 5000 K and 20 000 K. The importance of including accurate C1 expansions for both the target and the (N + 1)-electron terms is demonstrated. (Author)