Relativistic calculation of dielectronic recombination on the C4+ ground state

The relativistic multichannel theory has been applied and a nonperturbative formula adopted to calculate the dielectronic recombination cross section due to DeltaN = 1 resonances for the ground state C4+. The first-order appr oximation is adopted for the radiative process and a correction based on th e isolated resonance approximation is used for the very narrow resonances t o include the radiation width. The convoluted cross section is in agreement within 5% with, that of observation for resonances with n less than or equ al to 5. For n = 6 and 7, the integral cross section is overestimated by a factor of 6 and 4, respectively. According to our calculation, the Rydberg cut-off due to field ionization should be st a principal quantum number hig her than that given by Mannervik et al. A small relativistic effect is noti ced at intrashell resonance.