Results are presented for a theoretical model, known as the ion model
(IM), recently elaborated to calculate the radiative opacity of a hot
dense plasma. The model is based on the self-consistent field method f
or subsystems obeying Gibbs statistics. The results are compared with
calculations that use the Hartree-Fock-Slater model and with experimen
tal data. A theory is proposed to explain the extraordinary spectral l
ine-shift phenomenon associated with such plasmas.