Description
Collision strengths and thermally averaged collision strengths for a large number of extreme-ultraviolet lines of FeIX arising by electron impact have been reported. The thermally averaged collision strengths are calculated at electron temperatures in the range 10^4^-10^7^K for the 122043 forbidden and allowed transitions between the 370 fine-structure levels. The atomic parameters for FeIX play an important role in modeling of various astrophysical plasmas, including especially the solar corona. The B-spline Breit-Pauli R-matrix method has been used in the calculation of collision strengths. The target wave functions and transition probabilities have been determined by combining the multiconfiguration Hartree-Fock method with the B-spline box-based multichannel expansions. We have included 370 fine-structure levels of FeIX in the energy region up to 3s^2^3p^5^5s states. The close-coupling expansion includes levels of the 3s^2^3p^6^, 3s^2^3p^5^3d, 4l, 5s, 3s3p^6^3d, 4s, 4p, 3s^2^3p^4^3d^2^, 3s3p^5^3d^2^ configurations and some low-lying levels of the 3s^2^3p^3^3d^3^ configuration in our collision strengths and transition probabilities calculations. There is a good agreement with the previous R-matrix collision strength calculations by Storey et al. (2002, J/A+A/394/753) and Del Zanna et al. (2014, J/A+A/565/A77) for transitions between the lowest 17 levels of the 3s^2^3p^6^, 3s^2^3p^5^3d and 3s3p^6^3d configurations, especially for electron temperatures logT(K)>=5.0. The transitions between the first 17 levels are dominated by Rydberg series of resonances converging to the levels of the 3s^2^3p^4^3d^2^ configuration. The present results and the calculation of Del Zanna et al. show significant differences for many weaker forbidden and intercombination transitions with thermally averaged collision strengths smaller than 0.01.
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