Spline-Galerkin methods applied to Rydberg series between the 4s2Sand 3d2Dlimits of calcium

The recently introduced nonvariational spline-Galerkin method [T. Brage and C. Froese Fischer, Phys. Scr. 49, 651 (1994)] for Rydberg series is applied to the J=0, 1, 2, and 3 even states between the two first limits in neutral calcium. Energies for 3dnl levels up to n=15–20 are reported and the position of different perturbers belonging to the 4${\mathit{p}}^2$ and 4p5p configurations are investigated. The 4p5p ${}_{}{}^1{}_{}{}^{}$ ${\mathit{P}}_1$ level is predicted to have an excitation energy of about 61 200 ${\mathrm{cm}}^{\mathrm{-}1}$ and the 4p5p ${}_{}{}^3{}_{}{}^{}$D level is predicted at about 61 600–62 000 ${\mathrm{cm}}^{\mathrm{-}1}$, while the 4p5p ${}_{}{}^3{}_{}{}^{}$P is just at the 3d ${}_{}{}^2{}_{}{}^{}$D limit.