2010A&A...518A..64L

We present results for the electron-impact excitation of all Ne-like ions from Na⁺ to Kr²⁶⁺ obtained using the intermediate-coupling frame transformation R-matrix approach. For each ion's calculation, the close-coupling expansion is taken to be the 113 LS terms (209 levels) belonging to the configurations [1s²]2s²2p⁶, 2s²2p⁵{3,4,5}l, 2s2p⁶{3,4,5}l (l∈s, p, d, f, and g), and 2s²2p⁵{6,7}l' (l'∈s, p, and d). An additional configuration interaction effect arising from configurations of 2s²2p⁴3l{3,4,5}l'' (l''∈ s, p, d, f and g) was included in the target expansion. A detailed comparison of the target structure has been made for six specific ions (Si⁴⁺, Ar⁸⁺, Ca¹⁰⁺, Fe¹⁶⁺, Ni¹⁸⁺, and Kr²⁶⁺) spanning the sequence to assess the accuracy for the entire sequence. Effective collision strengths (Υs) are presented at temperatures ranging from 2x10²(q+1)²K to 2x10⁶(q+1)²K (where q is the residual charge of ions, i.e. Z-10). Detailed comparisons for the Υs are made with the results of previous calculations for several ions, which span the sequence. Furthermore, we examine the iso-electronic trends of effective collision strengths as a function of temperature. The present results are the only R-matrix ones for the majority of the ions and the most extensive and complete data for modelling to-date.