Calculations of strong interactions between a perturber and one or several series using B-spline basis sets

We use B-spline basis sets to consider the influence of complete series (i.e. discrete states + continuum) on a perturber. In particular we calculate the interaction between the nsnp 6 2 S term and the ns 2 np 4 ( 1 D)md/ epsilon d 2 S Rydberg series in Ar II (n = 3) and Kr II(n = 4) and between the 3s3p 5 3 P term and the 3p 3 ( 2 D)nd/ epsilon d 3 P, 3p 3 ( 2 P)nd/ epsilon d 3 P and 3p 3 ( 2 P)ns/ epsilon s 3 p Rydberg series in S I. Energies and eigenvectors are calculated for the lower part of the bound spectrum. In Ar II and Kr II, we use these to calculate the strength of the satellite spectrum following 3s ionization in Ar and 4s ionization in Kr. In the case of S I we calculate oscillator strengths for transitions to the ground state and discuss the identification of the observed photoabsorption spectra. The results are compared with other theoretical calculations and with experimental results. We discuss the determination of the B-spline basis as a solution to the frozen core HF equations. We show that use of a rather limited B-spline basis is a very efficient way to approximate a complete (bound + continuum) Rydberg series.