Modified Becke-Johnson potential investigation of half-metallic Heusler compounds

Abstract

We have investigated the electronic structures of various potentially\nhalf-metallic Heusler compounds with the Tran-Blaha modified Becke-Johnson\n(TB-mBJLDA) potential within the density functional theory. The half-metallic\ngaps are considerably enhanced with respect to values from the\nPerdew-Burke-Ernzerhof (PBE) functional. In particular the unoccupied densities\nof states are modified by mBJLDA, and agreement with experiment is considerably\nworse than for PBE. The agreement of the densities of states can be improved by\nreducing the Tran-Blaha parameter c. However, ground state properties such as\nthe hyperfine fields are more accurately described by PBE than by mBJLDA.\nDespite its success for ionic and covalent semiconductors and insulators, we\nconclude that mBJLDA is not a suitable approximation for half-metallic Heusler\ncompounds.\n