  We calculate target-material responses for dark matter--electron scattering
at the \textit{ab-initio} all-electron level using atom-centered gaussian basis
sets. The all-electron effects enhance the material response at high momentum
transfers from dark matter to electrons, $q\gtrsim \mathcal{O}\left({10\ \alpha
m_e}\right)$, compared to calculations using conventional plane wave methods,
including those used in QEDark; this enhances the expected event rates at
energy transfers $E \gtrsim 10$~eV, especially when scattering through heavy
mediators. We carefully test a range of systematic uncertainties in the theory
calculation, including those arising from the choice of basis set,
exchange-correlation functional, number of unit cells in the Bloch sum,
$\mathbf{k}$-mesh, and neglect of scatters with very high momentum transfers.
We provide state-of-the-art crystal form factors, focusing on silicon and
germanium. Our code and results are made publicly available as a new tool,
called Quantum Chemistry Dark (``QCDark'').
