Optimized-effective-potential method and hybrids Weitao Yang Duke University Chemistry Instead of using electron density as the explicit variable, it is possible to use orbitals or the density matrix as the explicit variable in density functional approximation, with a better accuracy potentially. The Hatree-Fock (HF) approximation is such a functional. The hybrid functionals combining HF with GGA will be discussed, including its motivation and performance. For such orbital functionals, there are two ways to carry out self-consistency calculations, the optimized effective potential and the generalized Kohn-Sham. The theory and implementation of OEP will be presented.