Energy levels, radiative rates, and electron impact excitation rates for transitions in Li-like ions with 12 <= Z <= 20

Abstract

We report calculations of energy levels, radiative rates, and electron impact excitation rates for transitions in Li-like ions with 12 <= Z <= 20. The GRASP (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates, while for determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code DARC is used. Oscillator strengths, radiative rates, and line strengths are reported for all E1, E2, M1, and M2 transitions among the lowest 24 levels of the Li-like ions considered. Collision strengths have been averaged over a Maxwellian velocity distribution, and the effective collision strengths obtained are reported over a wide temperature range up to 10$^{7.4}$ K. Additionally, lifetimes are also listed for all calculated levels of the above ions. Finally, extensive comparisons are made with available results in the literature, as well as with our parallel calculations for all parameters with the Flexible Atomic Code FAC in order to assess the accuracy of the reported results.