Effective Collision Strengths for Fine‐Structure Transitions from the 3s23p52PGround State of Chlorine–like Nixii

Abstract

The R-matrix method is used to compute electron impact collision strengths for transitions in Ni XII from its ground-state fine-structure levels. Sophisticated configuration-interaction wave functions are used to represent the 14 lowest LS target states employed in the R-matrix expansion. By transforming the LS-coupled reactance matrices, and by assuming a Maxwellian velocity distribution for the incident electrons, the effective collision strengths are calculated for the 3s -->23p -->5 -->2P -->o1/2-3s -->23p -->5 -->2P -->o3/2 transition within the ground state and from both these fine-structure levels to the 29 excited levels arising from states obtained from 3s3p6 and 3s23p43d configurations. Effective collision strengths, obtained in the temperature range log Te = 3.2-6.6 (K), are expected to have an accuracy of better than 20%.