Bound-Bound Transitions in LEDCOP

All of the bound-bound transition data for the LEDCOP opacity code is calculated by the Cowan self-consistent Hartree-Fock atomic physics code. Two types of atomic physics data are calculated.

The first type is single configuration LS term data, including the energies, radial dipole matrix elements and the angular factors. These are calculated for all elements up to phosphorus and for the simpler ionization stages and configurations of the other light elements up to zinc. The upper limit for these is on the order of 10,000 LS lines per transition array. Whenever possible, these numbers are modified by experimental observation.

The second type is unresolved transition array (UTA) energies and variances, using intermediate coupling. These are calculated for the more complex configurations, where it is possible to have millions of lines for each transition array. For moderately dense conditions, the UTA model allows us to replace all of these line transitions with a single UTA Gaussian profile. For less dense conditions, the UTA profile is replaced by a set of randomly generated lines (constrained by the UTA variances and strengths) of up to 40,000 lines. This allows us to approximate the million line transition arrays with a reasonable number of lines and to also prevent the over-estimation of the Rosseland opacity, which is weighted more by the valleys between the lines than the peak intensities.