Recent theories of Singwi et al. for the dielectric response beyond the random-phase approximation are examined in the density-functional formalism. Their approximation and another from the perturbation expansion in the electron-electron interaction are used to calculate the correction to the local-density approximation of the exchange energy in atoms. The latter gives better results.

• Received 22 December 1972

DOI:https://doi.org/10.1103/PhysRevB.7.4357