Statistical line-by-line model for atomic spectra in intermediate coupling

A statistical method to simulate detailed line accounting (DLA) calculations of complex spectra is proposed. The method is based on the recently developed partially resolved transition array model. Numerical examples show that spectrum calculations using the statistical approach are in good agreement with DLA results. In particular, the statistical method conserves systematic line coincidences across transition arrays differing only in the subshell occupation of excited spectator electrons important in opacity calculations. In addition, it is computationally efficient; hence, it can accelerate spectrum calculations without introducing significant uncertainties whenever the DLA method is considered impractical.