Term energies and radiative atomic data of carbon-like ions Na VI and Al VIII

Excitation energies belonging to the (1s²)2s²2p², 2s²2p³p, 2s²p³, 2s²2p³s, and 2s²2p³d configurations of carbon-like Na VI and Al VIII have been calculated with the multi-configuration Rayleigh-Ritz variation method and restricted variation method, as well as wavelengths, line strengths, oscillator strengths, transition rates for electric dipole transitions among these terms. High-accuracy calculations have been performed using a moderate scale of Slater basis function and accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects. The line strengths, transition oscillator strengths, and transition probabilities for the electric dipole transitions are determined. Deviations of line strengths between the length and velocity gauges are discussed, as well as with the experimentally compiled values from the National Institute for Standards and Technology (NIST) and other theoretical data wherever available. Furthermore, the accuracy of each electric dipole transition is assessed. The present results are accurate enough for identification of emission lines involving these terms and are also useful for precise spectral modeling and diagnosing in astrophysical and laboratory plasmas. (author)