Oscillator strengths for transitions to high-lying excited states of carbon

A spline frozen-cores method for treating Rydberg series is presented and applied to series in carbon. The method can be used for accurate calculations of oscillator strengths for states with high n -values, where standard multiconfiguration Hartree–Fock methods encounter difficulties. Energy levels and oscillator strengths for transitions from the 2p 2 ground configuration of carbon to 2p n d, n = 3–9, and 2p n s, n = 3–10, have been computed by this method in the Breit–Pauli approximation with non-orthogonal orbitals. The results are compared with the values predicted from astrophysical data, NIST tabulations and several theories.