Relativistic density-functional theory based on effective quantum electrodynamics

A relativistic density-functional theory based on a Fock-space effective quantum-electrodynamics (QED) Hamiltonian using the Coulomb or Coulomb-Breit two-particle interaction is developed. This QED properly includes effects of vacuum polarization through creation electron-positron pairs but does not include explicitly photon degrees freedom. It thus more tractable alternative to full for atomic and molecular calculations. Using constrained-search formalism, Kohn-Sham scheme formulated in quite similar way non-relativistic theory, some exact properties involved density functionals are studied, namely charge-conjugation symmetry uniform coordinate scaling. The usual no-pair obtained as well-defined approximation this theory.