  We perform first-principles path integral Monte Carlo (PIMC) and density
functional theory molecular dynamics (DFT-MD) calculations to explore warm
dense matter states of LiF. Our simulations cover a wide density-temperature
range of $2.08-15.70$~g$\,$cm$^{-3}$ and $10^4-10^9$~K. Since PIMC and DFT-MD
accurately treat effects of atomic shell structure, we find a pronounced
compression maximum and a shoulder on the principal Hugoniot curve attributed
to K-shell and L-shell ionization. The results provide a benchmark for
widely-used EOS tables, such as SESAME, LEOS, and models. In addition, we
compute pair-correlation functions that reveal an evolving plasma structure and
ionization process that is driven by thermal and pressure ionization. Finally,
we compute electronic density of states of liquid LiF from DFT-MD simulations
and find that the electronic gap can remain open with increasing density and
temperature to at least 15.7 g$~$cm$^{-3}$.
