Electron impact excitation for P-like Ni XIV

Abstract

In this paper we report the calculations on effective collision strengths for electron impact excitations among the 41 levels of 3s23p3, 3s3p4 and 3s23p23d configurations in Ni XIV. The Dirac R-matrix theory and the relativistic distorted-wave method in conjunction with isolated resonance approximation are adopted for the calculations. Detailed comparisons between the results obtained from the above two methods show that the independent process and isolated resonance approximation using distorted waves can describe the near threshold resonances reasonably well for most transitions in Ni XIV, though channel-coupling effects are found to be important for weak transitions. Resonances enlarge significantly the effective collision strengths for many transitions, even by over two orders of magnitude.