Mean-force scattering potential for calculating optical properties of dense plasmas

We assess the relative importance of ionic structure on the opacity of dense plasmas by using the potential of mean force as a scattering potential within the Kubo-Greenwood formalism. We compare results from the potential of mean force, which includes realistic ionic structure, to results using an average atom potential, which includes only a crude treatment of ionic structure. Comparisons with less approximate but more expensive DFT-MD simulations for aluminum plasma reveal that the mean force generally improves agreement for DC conductivity. We also see improvement when applying the mean force to free-free transitions, whereas for bound-bound and bound-free transitions the mean force leads to poorer agreement on transition energies. Further, we assess the impact of accounting for correlations within the plasma at the temperature and density conditions relevant to iron opacity measurements at Sandia’s Z machine facility [Bailey et al., Nature 517:56-59, 2015] and find that these correlations do not account for the discrepancy between the measurements and leading opacity calculations.