Energy levels and oscillator strengths for neutral calcium

The wavefunctions and energy levels of the low-lying spectrum of the neutral calcium atom are computed using the configuration interaction method. The Hamiltonian for the two valence electrons is modified by the addition of a semi-empirical polarization potential. The inclusion of the polarization potential results in theoretical energy levels in much closer agreement with experiment. The largest discrepancy between the computed and experimental energies (relative to the Ca 2+ limit) is smaller than 0.1 eV. Oscillator strengths are computed for all possible dipole transitions and found to be in better accord with experiment that previous calculations. Lifetimes are also computed and compared with experiment for those levels where lifetime data exists.