Optimized effective potentials for semiconductors

We calculate atomic and crystal total energies, the equilibrium lattice constant, bulk modulus, and energy gaps for Si using the optimized effective potential for a Hamiltonian containing the Fock operator and a local-density approximation (LDA) correlation functional. These results are compared with those obtained from ordinary LDA and Hartree-Fock--core LDA--valence calculations and experiment. The results are consistent with those we previously obtained for Ge. We note a difficulty in applying pseudopotentials to the optimized effective potential and describe how to overcome it.