where ω T NL [ρ](r, r ′ ) is the kernel of the non-local functional while α and β are positive exponents. Commonly, the linear response of the electron gas, which is described analytically by the Lindhard function, is used as exact constraint in the construction of such KEDFs. This non-local part can be evaluated efficiently in reciprocal space [where the kernel becomes ω T NL [ρ](q)], which currently limits the applicability of non-local KEDFs to periodic systems.