Computational modeling of scattering processes in warm dense beryllium

Accurate predictions of electrical and thermal conductivities play an important role in the design of inertial confinement fusion (ICF) targets, where they can affect compression, instability growth, and energy losses. The warm dense matter (WDM) regime, with near-solid densities and temperatures above ~1 eV (10 kK), is particularly difficult to model due to the confluence of degeneracy, thermal, and strong coupling effects. Here, we study electron-electron (el-el) and electron-phonon (el-ph) scattering processes in beryllium, a common ICF material, in the WDM regime from first principles. Specifically, we find el-el 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. From this data, we predict el-el lifetimes on the order of hundreds of fs near the Fermi energy and tens of fs under excitations of 1 eV. We also simulate time-dependent el-ph relaxation dynamics by solving the Boltzmann transport equation, helping us to disentangle the relative importance of both processes. Revelations from this work will improve collision frequencies and scattering cross sections entering conductivity models used for ICF target design.