Effective collision strengths for electron‐impact excitation of transitions within the ground 1 s 2 2 s 2 2 p 4 manifold of O‐like Fe 18+

Collision strengths have been computed for the electron impact excitations of parity and spin forbidden transitions within the ground 1 s 2 2 s 2 2 p 4 manifold of Fe XIX (Fe 18+ ). The calculations were carried out using a relativistic R‐matrix close‐coupling method based on the effective many‐body Hamiltonian. Twenty‐six target states were included in the close‐coupling expansion. Effective collision strengths, assuming a Maxwellian electron velocity distribution, were evaluated for all transitions within the ground configuration. Good agreement is found with previous Breit‐Pauli R‐matrix calculations at low electron temperatures, 5.0 ≤ log T e ≤ 6.0 K, for all the transitions, whereas significant differences are found for electron temperatures in the range 6.0 ≤ log T e ≤ 7.0 K. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009