Extensions of the opacity project: Transition probabilities for dipole allowed fine structure transitions in Si-like ions: Si I, S III, Ar V, and Ca VII

Oscillator strengths and radiative transition probabilities for dipole allowed fine structure levels are obtained for Si-like ions: Si I, S III, Ar V, and Ca VII from LS multiplet line strengths calculated for the Opacity Project (OP). The radiative calculations for the OP are carried out in the close-coupling approximation employing the R-matrix method as developed for the OP. An extension of the OP is made to calculate the fine structure f-values for the individual transitions within the multiplets through an algebraic transformation of the. LS line strengths to fine structure components. In addition, the calculated fine structure f-values are obtained using observed energy levels and are thus an improvement over the original OP data that use the calculated energies. There are little previous data available for the transition probabilities for these ions. Comparisons of the present oscillator strengths and the lifetimes with available experimental values exhibit good agreement in general, particularly for Si I