Collision strengths and rate coefficients for excitation of He-like ions by electron impact

We present collision strengths and rate coefficients for electron-impact excitation of He-like ions (S14+, Ar16+, Ca18+) using the Dirac Atomic R-matrix Code, which has been developed by Norrington and Grant [J. Phys. B: At. Mol. Opt. Phys. 20 (1987) 4869]. The lowest 45 target levels are included in the calculation to obtain the rate coefficients for the 1s21S0-1snl1,3LJ (n = 2, 3, 4; l = 0, 1, 2, 3). Results are compared with those available in previous calculations.