19.1.30 S: Slater-Dirac Exchange Energy

J. C. Slater, Phys. Rev. 81, 385 (1951)

$$K= -c\sum_s \rho_{s}^{4/3} ,$$ (166)

where

$$c=\frac{3}{2}\left (\frac{3}{4\pi}\right )^{1/3}$$ (167)