Collision Strengths for Electron Impact Excitation of Fine‐Structure Levels in Fe xiii

Electron collisional excitation strengths for transitions among the fine-structure levels of the ground 3 s 2 3 p 2 configuration and from the levels of 3 s 2 3 p 2 configuration to the levels of the excited 3 s 3 p 3 and 3 s 2 3 p 3 d configurations in Fe XIII are calculated using a semirelativistic R -matrix approach. We considered 14 LS 3 s 2 3 p 2 3 P , 1 D , 1 S , 3 s 3 p 3 3 D o , 3 P o , 1 D o , 3 S o , 1 P o , 3 s 2 3 p 3 d 3 P o , 1 D o , 3 D o , 3 F o , 1 F o , and 1 P o states of Fe XIII in the present calculation. The 14 LS states give rise to 26 fine-structure levels that are represented by configuration-interaction wave functions. The relativistic effects are included in the Breit-Pauli approximation via one-body mass correction, Darwin, and spin-orbit interaction terms in the scattering equations. Complicated resonance structures are explicitly included in the collision strengths. The collision strengths are integrated over a Maxwellian distribution of electron energies to give effective collision strengths over a wide temperature range from 5 × 10 5 to 5 × 10 6 K.