  We quantify the accuracy of different non-self-consistent and self-consistent
spin-orbit coupling (SOC) treatments in Kohn-Sham and hybrid density-functional
theory by providing a band structure benchmark set for the valence and
low-lying conduction energy bands of 103 inorganic compounds, covering chemical
elements up to Po. Reference energy band structures for the PBE density
functional are obtained using the full-potential (linearized) augmented plane
wave code Wien2k, employing its self-consistent treatment of SOC including
Dirac-like p$^{1/2}$ orbitals in the basis set. We use this benchmark set to
benchmark a computationally simpler, non-self-consistent all-electron treatment
of SOC based on scalar-relativistic orbitals and numeric atom-centered orbital
basis functions. For elements up to Z$\approx$50, both treatments agree
virtually exactly. For the heaviest elements considered (Tl, Pb, Bi, Po), the
band structure changes due to SOC are captured with a relative deviation of 11%
or less. For different density functionals (PBE vs. the hybrid HSE06), we show
that the effect of spin-orbit coupling is usually similar but can be dissimilar
if the qualitative features of the predicted underlying scalar-relativistic
band structures do not agree. All band structures considered in this work are
available online via the NOMAD Repository to aid in future benchmark studies
and methods development.
