EXACT TREATMENT OF EXCHANGE IN KOHN-SHAM BAND-STRUCTURE SCHEMES

A Kohn-Sham (KS) scheme for solids treating exchange exactly is introd uced. The scheme emerges from a recently introduced exact formal KS pr ocedure [A. Gorling and M. Levy, Phys. Rev. A 50, 196 (1994)]. The exa ct density-functional exchange potential is obtained in terms of its F ourier components. The method can easily be implemented on the basis o f existing Hartree-Fock schemes for solids employing plane waves as ba sis sets.