PUB - Publikationen an der Universität Bielefeld

We have investigated the electronic structures of various potentially half-metallic Heusler compounds with the Tran-Blaha modified Becke-Johnson + local density approximation (TB-mBJLDA) potential within the density functional theory. The half-metallic gaps are considerably enhanced with respect to values from the Perdew-Burke-Ernzerhof (PBE) functional. In particular the unoccupied densities of states are modified by the mBJLDA potential, and agreement with experiment is considerably worse than for PBE results. The agreement of the densities of states can be improved by reducing the Tran-Blaha parameter c. However, ground-state properties such as the hyperfine fields are more accurately described by the PBE functional than by the mBJLDA. Despite its success for ionic and covalent semiconductors and insulators, we conclude that the mBJLDA is not a suitable approximation for half-metallic Heusler compounds. DOI: 10.1103/PhysRevB.87.045103