A frozen cores approximation for atomic structure calculations

The coupled integro-differential equations for electron collisions with an N-electron ion may be solved at energies which give bound states for the (N+1)-electron system. Results are obtained for the 1 P 0 series in C 2+ , including the configurations 1s 2 2snp, 1s 2 2pn's, 1s 2 2pn"d and 1s 2 2s2p. The 1s, 2s and 2p radial functions are calculated for C 3+ and the np, n's and n"d radial functions are solutions of the coupled integro-differential equations.