General operator ground-state expectation values in the Hohenberg-Kohn-Sham density-functional formalism

Explicit density functionals are constructed for the ground-state expectation values of arbitrary quantum-mechanical operators in terms of the solutions of the Kohn-Sham self-consistent equations and well-defined correction terms. The one-particle Green function, and consequently quasiparticle excitation energies, and the one-particle density matrix are, for example, expressible in this way. Implications for the practice of electronic structure calculations are discussed.