Relationship between Slater and Kohn-Sham exchange potentials

It is shown that an exchange potential proposed by Slater in 1951 can be obtained as the partial functional derivative with respect to charge density of an exchange energy functional. Calculations on atomic neon demonstrate that this potential yields considerably better eigenvalues and total energies than the local-density approximation and remarkably better results when applied to valence electrons only. Its application to solids or liquids is shown to be computationally straightforward.