@article{bernardi_physical_2020,
	title = {Physical origin of the one-quarter exact exchange in density functional theory},
	volume = {32},
	url = {https://dx.doi.org/10.1088/1361-648X/ab9409},
	doi = {10.1088/1361-648X/ab9409},
	abstract = {Exchange interactions are a manifestation of the quantum mechanical nature of the electrons and play a key role in predicting the properties of materials from first principles. In density functional theory (DFT), a widely used approximation to the exchange energy combines fractions of density-based and Hartree–Fock (exact) exchange. This so-called hybrid DFT scheme is accurate in many materials, for reasons that are not fully understood. Here we show that a 1/4 fraction of exact exchange plus a 3/4 fraction of density-based exchange is compatible with a correct quantum mechanical treatment of the exchange energy of an electron pair in the unpolarized electron gas. We also show that the 1/4 exact-exchange fraction mimics a correlation interaction between doubly-excited electronic configurations. The relation between our results and trends observed in hybrid DFT calculations is discussed, along with other implications.},
	number = {38},
	journal = {Journal of Physics: Condensed Matter},
	author = {Bernardi, Marco},
	month = jun,
	year = {2020},
	note = {Publisher: IOP Publishing},
	pages = {385501},
}