  Density functional theory (DFT) is widely used to predict chemical
properties, but its accuracy is limited by functional approximations and their
approximate self-consistent densities. Density-corrected DFT (DC-DFT) is the
study of the errors due to densities and Hartree-Fock DFT (HF-DFT) uses HF
densities to improve energetics. With increasing use of HF-DFT, the question of
how to address strong spin contamination in the HF calculation becomes
increasingly important. We compare two different open-shell HF densities across
13 different DFT functionals and two DC-DFT methods. For significant spin
contamination, ROHF densities outperform UHF densities by as much as a factor
of 3, depending on the energy functional, and ROHF-DFT improves over
self-consistent DFT for most of the tested functionals. We refine the
DC(HF)-DFT algorithm, recommending ROHF-DFT in cases of severe spin
contamination.
