2008 Articles

Orbital sensitivity in Mg2+ dielectronic recombination calculations

Savin, Daniel Wolf; Fu, J.; Gorczyca, T. W.; Nikolic, D.; Badnell, N. R.; Gu, M. F.

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.