A hybrid detailed level and configuration accounting model for investigating the radiative opacity of gold plasmas with open 4d and 4f shells

A hybrid model combining the detailed level accounting (DLA) and detailed relativistic configuration accounting (DCA) methods is developed to investigate the radiative opacity of gold plasmas with open 4d and 4f shells. Due to the collapse of 4f shells, the configurations with multi-electron excited from 4d and 4f shells are bound and can form a huge number of fine-structure levels and detailed transition lines. A full DLA calculation is time-consuming and intractable and thus a hybrid DLA and DCA method is needed. To obtain accurate radiative opacity, the transitions within the collapsed orbitals and transitions to the relatively lowly excited orbitals are treated by a DLA method, while the transitions to the higher excited orbitals are treated by a DCA method. As an illustrative example, the spectrally resolved, Rosseland and Planck mean opacity of gold plasmas at 100 eV and 0.001 g/cm3 are calculated by using the hybrid model. The present results are compared with those obtained by pure DCA and average atom models, where large discrepancies in the line intensities and positions are found for the strongest 4d-4f transitions due to the collapse of 4f shells indicating the importance of detailed treatment to obtain the accurate opacity.