Optical Response Properties and Effective Charges of Warm Dense Matter Mixtures

Predicting the charged particle transport properties of warm dense matter/hot dense plasma mixtures is a challenge for analytical models. High accuracy ab initio methods are more computationally expensive but can provide critical insight by explicitly simulating mixtures. In this work, we use Kohn-Sham Density Functional Theory to investigate the transport properties and optical response of warm dense mixtures at varying concentrations under either conserved electronic pressure or mass density at a constant temperature. We compare options for mixing the calculated pure species properties to estimate the results of the mixtures. We find that a combination of the Drude model with the Matthiessen's rule works well for DC electron transport and low-frequency optical response. This breaks down at higher frequencies, where a volumetric mix of pure-species AC conductivities works better. We will also highlight a novel method for extracting the effective charge state and elemental conductivities from multi-atom simulations of disordered mixtures using time-dependent density functional theory.