Collision strengths for electron impact excitation of fine-structure: Levels in Fe XIII

Electron collisional excitation strengths for transitions among the fine-st ructure levels of the ground 3s(2)3p(2) configuration and from the levels o f 3s(2)3p(2) configuration to the levels of the excited 3s3p(3) and 3s(2)3p 3d configurations in Fe XIII are calculated using a semirelativistic R-matr ix approach. We considered 14 LS 3s(2)3p(2 3)P, D-1, S-1, 3s3p(3) D-3(0), P -3(0), D-1(0), S-3(0), P-1(0), 3s(2)3p3d P-3(0), D-1(0), D-3(0), F-3(0), F- 1(0), and P-1(0) states of Fe XIII in the present calculation. The 14 LS st ates give rise to 26 fine-structure levels that are represented by configur ation-interaction wave functions. The relativistic effects are included in the Breit-Pauli approximation via one-body mass correction, Darwin, and spi n-orbit interaction terms in the scattering equations. Complicated resonanc e structures are explicitly included in the collision strengths. The collis ion strengths are integrated over a Maxwellian distribution of electron ene rgies to give effective collision strengths over a wide temperature range f rom 5 x 10(5) to 5 x 10(6) K.