Gradient-corrected pseudopotential calculations in semiconductors

We have computed cohesive properties for Si, Ge, and GaAs in the framework of pseudopotential density-functional theory, including gradient corrections to the local-density approximation (LDA). Computed cohesive energies are in significantly better agreement with experiment than those given by the LDA, while lattice constants show only a minor improvement. The Kohn-Sham single-particle spectrum reveals a systematic k-dependent repulsion between occupied and unoccupied states. Finally we discuss the screening properties of a gradient-corrected homogeneous electron gas.