Self-consistent band-gap corrections in density functional theory using modified pseudopotentials

Density functional calculations based on the local density approximation or generalized gradient approximation have proven their value for predicting ground-state properties of materials. However, the corresponding band structures cannot be directly compared with experiment. We describe an approach based on a modification of pseudopotentials, in the spirit of a technique proposed by Christensen [Phys. Rev. B 30, 5753 (1984)]. These pseudopotentials still accurately describe structural properties and energetics, but they also produce band structures in better agreement with experiment. We establish reliability by performing extensive tests and comparisons with other methods, and illustrate the approach with applications to electronic stucture of bulk, point defects, and surfaces of nitride semiconductors.