Theoretical study of the atomic spectra of the calcium atom

Theoretical calculations are reported for the following terms of the atomic spectra of the Ca atom: 1S(4s2), 1P(4s4p), 3P(4s4p), 1D(4s3d), 3D(4s3d), 1P(4s5p), 3P(4s5p). The method is based on all-electron calculations at the Hartree—Fock level followed by a configuration interaction for the two valence electrons. Core—valence (or intershell) correlation effects are introduced via a second-order perturbation development or via a core-polarization potential. The agreement with the experimental spectra is very good.