Electronic structure calculations are a valuable tool in the analysis of positron annihilation experiments. Calculations predict measured quantities such as positron lifetimes and momentum distributions of annihilating electron-positron pairs corresponding to vacancy-type defects trapping effectively free positrons. In this work we present a scheme for the calculation of momentum distributions of annihilating electron-positron pairs using the density-functional theory. Valence electron states and the potential are described by using the projector augmented-wave method and plane-wave expansions. Free atom wave functions are used for core electrons. The corresponding positron states are solved by a real-space calculation method. We present also some recent examples of the application of the scheme to studying vacancy-type defects in semiconductors.
Fields of Science
- 114 Physical sciences