A Superconﬁguration Calculation of Opacity with Consistent Bound and Continuum Electron Treatments Using Green’s Functions


 One of the challenges in calculating the opacity of dense plasmas is the diﬃculty in consistently modeling electrons bound to nuclei and those that exist within the continuum of free states in electronic structure models. We address this issue by adapting the Green’s function approach, originally developed for use in average atom calculations, to the determination of superconﬁguration electronic structure. The spectra created using these superconﬁgurations indicate that a consistent treatment of continuum electronic structure is important for phenomena involving electrons near ionization thresholds, such as the pressure ionization of bound states and the opacity due to transitions near bound-free edges. Though important for dense plasmas, the detailed incorporation of continuum electrons into structure calculations does not have signiﬁcant impact on the recent discrepancies between the predicted and measured opacity of hot, dense iron [J. E. Bailey et al., Nature (London) 517, 56 (2015)]. We ﬁnd that the inclusion of plasma eﬀects through an ion-sphere model along with our treatment of continuum electronic states gives a description of pressure ionization in hot, dense aluminum that is in better agreement with experiment than methods that rely on perturbative descriptions of the plasma environment [D. J. Hoarty et al., Phys. Rev. Lett. 110, 265003 (2013)].