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**Session 54 - Ground and Instrumentation Techniques and Catalogs.**

*Display session, Wednesday, June 12*

*Tripp Commons, *

## [54.17] The Iron Project: Atomic Data for the Iron Peak Elements

*A. K. Pradhan, H. L. Zhang, S. N. Nahar, M. A. Bautista (Ohio State U.)*
Emission and absorption lines from Iron ions are of great importance as
diagnostics for a large variety of objects and in most wavelength ranges,
from the X-ray and extreme UV up to the far IR.
The IRON Project is an international collaboration devoted to the study of
atomic processes and
the calculation of collisional and radiative data
for ions of the iron-peak elements for
applications in astrophysical and laboratory plasmas.
The ab initio atomic calculations are carried out in the close-coupling
approximation, using the R-matrix
method and a package of codes developed for the Opacity Project and
extended to include relativistic effects in the Breit-Pauli
approximation. Parameters for many of the atomic processes of importance in
astrophysics are calculated: (i) photoionization cross sections,
(ii) total e-ion recombination rates including both the radiative and di-electr
onic recombination processes, (iii)
collision strengths, and (iv) radiative transition probabilities.
Selected results will be presented for Fe I, Fe II,
Fe III, Fe IV, Fe V, Fe XXII, Fe XXV, and Ni II. Of particular interest
are the results for the low ionization stages of Iron: Fe I,II, and III, for
which the new photoionization cross sections and corresponding
recombination rates, both computed in a self-consistent manner for the
first time, differ from the data currently in use in astrophysical
models by up to several orders of magnitude.
Also, at Ohio State, a parallelized version of the R-matrix codes
has been developed for the massively parallel machine Cray T3D, thus
enhancing the computational capabilities needed for such extensive
calculations.
The work is supported partially by the U.S. National Science Foundation
(PHY-9421898), the NASA LTSA program (NAGW-3315) and the
NASA ADP program (NAS5-32643).

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