Coupling effects in electron-impact excitation of oxygen-like krypton

Coupling effects among the channels for collisional excitation of 2s22p4, 2s2p5, and 2p6 configurations of oxygen-like krypton have been investigated by comparing six-, five-, four-, three-, and two-state close-coupling (CC) cross sections for the electron collision energy range 26.2 Ry≤E≤500 Ry. We discovered the surprising result that the calculated three-state CC (3CC) cross sections for the transition from the ground state to the 2p61S/sup e/ and the two-state CC cross section to the other excited states are reduced [considerably (45%) for the former] when the 2s2p53P/sup o/ channel is added to the 5CC approximation. In addition, the 3CC cross section σ(2p43P/sup e/--2p61S/sup e/) is diminished by a factor of 100 at 26.2 Ry by the addition of the 2s2p53P/sup o/ state. Approximations which omit the 2s2p53P/sup o/ state overestimate the cross sections