  The reduced basis method is used to construct a "universal" basis of Dirac
orbitals that may be applicable throughout the nuclear chart to calibrate
covariant energy density functionals. Relative to our earlier work using the
non-relativistic Schr\"odinger equation, the Dirac equation adds an extra layer
of complexity due to the existence of negative energy states. However, once
this problem is mitigated, the resulting reduced basis is able to accurately
and efficiently reproduce the high-fidelity model at a fraction of the
computational cost. We are confident that the resulting reduced basis will
serve as a foundational element in developing rapid and accurate emulators. In
turn, these emulators will play a critical role in the Bayesian optimization of
covariant energy density functionals.
