We have investigated the reason for significant discrepancies between the results of two recent, similar computational methods [Zatsarinny et al., Astron. Astrophys. 426, 699 (2004); Gu, Astrophys. J. 590, 1131 (2003)] for dielectronic recombination (DR) of Mg2+. It is found that the choice of orbital description can lead to discrepancies by as much as a factor of 2 between total peak DR rate coefficients resulting from otherwise-identical computations. These unexpected differences are attributed to the large sensitivity to bound-orbital relaxation and continuum-orbital description effects on the computed radiative and autoionizing transitions arising from accidental cancellation. In order to obviate these effects, an approach, using a separate, nonorthogonal orbital basis for each configuration, is employed to yield a DR rate coefficient that we assess to be more reliable than all earlier published results.
- dielectronic recombination
- orbital description