Total electron-ion recombination of Fe III

It is shown that a method for calculating unified total electron-ion recombination rates, incorporating both the radiative and dielectronic recombination processes, can be applied to substantially complex atomic systems where a large number of recombination channels need to be coupled in an ab initio manner. Calculations are carried out for the astrophysically important ion Fe III, and total and state-specific recombination rate coefficients are obtained for e1 Fe IV → Fe III, in the close coupling approximation employing the R-matrix method. The calculations correspond to a 49-state eigenfunction expansion for the Fe IV core that includes states from the ground configuration 3d and the excited configurations 3d4s and 3d4p for proper treatment of the electron correlation effects. This is an accurate and detailed atomic calculation for the recombination rates for Fe III. The present rates are up to an order of magnitude lower than the previous values obtained through the Burgess general formula at electron temperatures where dielectronic recombination dominates.