Conductivity predictions for warm dense beryllium from first principles

Accurate understanding of scattering processes in the warm dense matter (WDM) regime leads to improvements in electrical and thermal conductivity predictions that are essential in the design of inertial confinement fusion (ICF) experiments. In our approach, we use first-principles calculations to study electron-electron (e-e) and electron-phonon (e-ph) scattering processes in warm dense beryllium with near solid density and electronic temperatures greater than 0.5 eV. The standard method for WDM conductivity calculations, based on the Kubo-Greenwood formula, does not properly describe e-e or e-ph scattering processes. We calculate e-e lifetimes by fitting the imaginary part of the self-energy from many-body perturbation theory GW calculations to the Landau theory of the Fermi liquid, where we find the fitting parameter to be 0.018 eV^-1. We also study the carrier dynamics of excited electrons, represented by a Gaussian distribution of the Kohn-Sham states, centered 1-3 eV above the Fermi energy, arising from e-ph scattering, via solving the Bolzmann transport equation (BTE). This yields predictions of quantities such as relaxation times towards a Fermi distribution. We estimate that our results could alter predictions used to model ICF experiments by about a factor of two.