Close-coupling R-matrix calculations for electron-ion recombination cross sections

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Title: Close-coupling R-matrix calculations for electron-ion recombination cross sections
Creators: Zhang, Hong Lin; Nahar, Sultana Nurun; Pradhan, Anil K.
Issue Date: 1999
Citation: Zhang, Hong Lin, Nahar, Sultana Nurun, Pradhan, Anil K "Close-coupling R-matrix calculations for electron-ion recombination cross sections," Journal of Physics B: Atomic, Molecular and Optical Physics, 32, (1999) p. 1459-1479.
DOI: 10.1008/0953-4075/39/8/005
Abstract: Close-coupling (CC) calculations of electron-ion recombination cross sections using the R-matrix method are presented and benchmarked with available experimental measurements. The electron-ion recombination process, including resonant and non-resonant recombination may be unified as a natural extension of the coupled-channel approximation, as traditionally employed for photoionization and electron-ion scattering. Recombination cross sections can be calculated to the same accuracy by employing similar eigenfunction expansions for the target ion. Detailed results are obtained for electron recombination with C V, C VI, O VIII and Fe XXV. Several sets of theoretical calculations are reported and discussed: non-relativistic CC in LS coupling, relativistic CC in the Breit-Pauli approximation, with radiative attenuation and fine structure, and the relativistic distorted-wave approximation. The theoretical results are in very good agreement with highly accurate experimental measurements at the Heidelberg test storage ring for C V, C VI and O VIII, and the electron-ion beam trap at Livermore for Fe XXV. We discuss the overall effect of radiation damping of all resonances on effective cross sections and rates, important for H-and He-like ions. In addition to agreement with experimental data, the validity of the CC calculations is demonstrated by the continuity between the calculated photorecombination, dielectronic recombination and electron impact excitation cross sections. Certain issues related to the works of Badnell et al (1998 J. Phys. B: At. Mol. Opt. Phys. 31 L239) and Robicheaux (1998 J. Phys. B: At. Mol. Opt. Phys. 31 L109) are also addressed.
ISSN: 0953-4075
Rights: © IOP Publishing Ltd
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