R-Matrix calculations of astrophysical opacities (RMOP)

Abundances of elements in the Universe are uncertain. Even in the Sun

the discrepancies are up to 30-40% for common elements C, N, O and Ne.

The primary problem is the intricate interplay of atomic and plasma

physics of opacities that govern radiation transport.

In order to address this "solar problem", and discrepancies among

current theoretical models and experiments,

an extended version of the R-matrix methodology is employed to compute

iron opacity accurately, especially due to

prominent Fe ions that contribute significantly to overall opacity at

the radiative/convection zones boundary in the Sun.

In addition to atomic calculations of heretofore unprecedented

complexity using the Breit-Pauli R-Matrix method (BPRM), a new

theoretical and computational formalism has been developed to

incorporate plasma effects due to thermal, collisional, Stark,

free-free transitions and core excitations, as function of temperatures

and densities, particularly those prevailing in high-energy-density (HED)

plasmas.