Effective Collision Strengths for Electron-Impact Excitation of Transitions Within the Ground 1s(2)2s(2)2p(4) Manifold of O-like Fe18+

摘要

Collision strengths have been computed for the electron impact excitations of parity and spin forbidden transitions within the ground 1s(2)2s(2)2p(4) manifold of Fe XIX (Fe18+). 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.