Autoionizing states in electron-impact ionization of C3+

Results are reported for electron-impact ionization of C3+ in the energy ra nge 290-350 eV using the R-matrix with pseudo-states method (RMPS). Pseudo- states and autoionizing states are explicitly included in the R-matrix expa nsion to take fully into account for the first time the interaction between the direct and indirect ionization processes. The calculated resonance str ucture in the ionization cross section is in good agreement with the experi ment of Muller et al but there is a small discrepancy in the normalization of the cross section between theory and experiment.