Benchmarking Conductivities from Average Atom Methods to Density Functional Theory for Warm Dense Matter*

Accurate and efficient calculations of electrical conductivities of warm dense matter (WDM) enable design and interpretation of laboratory WDM experiments. In this context, average atom (AA) methods commonly use the Ziman framework, which gives widely varying predictions depending on, e.g., models chosen for the ion-ion static structure factor and scattering cross sections. Here, we benchmark and constrain AA results against density functional theory (DFT) calculations with the Kubo-Greenwood formula. We consider solid-density beryllium at temperatures of 0.1, 0.5, and 1 eV and compare densities of state, dielectric functions, and dynamic conductivities. We find good agreement for frequencies above 5 eV and explore first-principles approaches for modeling electron-ion and electron-electron couplings affecting the low-frequency Drude contribution. This work forms a crucial component of broader efforts to benchmark and improve AA methods.