EFFECTIVE COLLISION STRENGTHS FOR FINE-STRUCTURE TRANSITIONS FROM THE3S(2)3P(5) P-2 GROUND-STATE OF CHLORINE-LIKE NI-XII

The R-matrix method is used to compute electron impact collision stren gths for transitions in Ni XII from its ground-state fine-structure le vels. Sophisticated configuration-interaction wave functions are used to represent the 14 lowest LS target states employed in the R-matrix e xpansion. By transforming the LS-coupled reactance matrices, and by as suming a Maxwellian velocity distribution for the incident electrons, the effective collision strengths are calculated for the 3s(2)3p(5 2)P (1/2)(0)-3s(2)3p(5 2)P(3/2)(0) transition within the ground state and from both these fine-structure levels to the 29 excited levels arising from states obtained from 3s3p(6) and 3s(2)3p(4)3d configurations. Ef fective collision strengths, obtained in the temperature range log T-e =3.2-6.6 (K), are expected to have an accuracy of better than 20%.