DC24: A new density coherence functional for multiconfiguration density‐coherence functional theory

In this study, we explored several alternative functional forms to construct more accurate and more physical density coherence (DC) functionals for multiconfiguration density‐coherence functional theory. Each functional is parameterized against the same database as used in our previous work. The best DC functional, which is called DC24, has a more physical interpretation, and—as a side benefit—it also has a mean unsigned error of 1.73 kcal/mol, which is a 9% improvement as compared to the previous functional. The article also contains a new definition of the unpaired electron density, which may be useful in other contexts as well.