Positron energy levels in narrow gap semiconductors

We have studied the behaviour of a positron in InxGa1−xSb and InAsx Sb1−x alloys by calculating their energy levels at different points of the reciprocal space at normal and under low pressure. The calculations are performed with the pseudopotential method and the virtual crystal approximation which incorporates the disorder effect as an effective potential coupled with the independent particle approximation. These energies determine quantities such as the positron and positronium work function and the deformation potentials which are important parameters in slow-positron beam experiments.