Ab initio path integral Monte Carlo simulations of warm dense two-component systems without fixed nodes: structural properties

We present extensive new \emph{ab initio} path integral Monte Carlo (PIMC) results for a variety of structural properties of warm dense hydrogen and beryllium. To deal with the fermion sign problem – an exponential computational bottleneck due to the antisymmetry of the electronic thermal density matrix – we employ the recently proposed [$\mathit{\text{J.}}\mathit{\text{Chem.}}\mathit{\text{Phys.}}$~$\mathbf{\text{157}}$, 094112 (2022); $\mathbf{\text{159}}$, 164113 (2023)] $\xi$-extrapolation method and find excellent agreement with exact direct PIMC reference data where available. This opens up the intriguing possibility to study a gamut of properties of light elements and potentially material mixtures over a substantial part of the warm dense matter regime, with direct relevance for astrophysics, material science, and inertial confinement fusion research.