An extended version of the R-matrix methodology is presented for calculation
of radiative parameters for improved plasma opacities. Contrast and comparisons
with existing methods primarily relying on the Distorted Wave (DW)
approximation are discussed to verify accuracy and resolve outstanding issues,
particularly with reference to the Opacity Project (OP). Among the improvements
incorporated are: (i) large-scale Breit-Pauli R-matrix (BPRM) calculations for
complex atomic systems including fine structure, (ii) convergent close coupling
wave function expansions for the (e+ion) system to compute oscillator strengths
and photoionization cross sections, (iii) open and closed shell iron ions of
interest in astrophysics and experiments, (iv) a treatment for plasma
broadening of autoionizing resonances as function of energy-temperature-density
dependent cross sections, (v) a "top-up" procedure to compare convergence with
R-matrix calculations for highly excited levels, and (vi) spectroscopic
identification of resonances and bound \eion levels. The present R-matrix
monochromatic opacity spectra are fundamentally different from OP and lead to
enhanced Rosseland and Planck mean opacities. An outline of the work reported
in other papers in this series and those in progress is presented. Based on the
present re-examination of the OP work, it is evident that opacities of heavy
elements require revisions in high temperature-density plasma sources.Comment: 16 pages, 2 figure