Intra-d excitations: Comparison between approaches for impurities in semiconductors

We present a comparison between two approaches—the linear combination of atomic orbitals–configuration interaction approach and the multiplet method developed by Fazzio, Caldas, and Zunger—to study excitation spectra of transition-metal impurities in a semiconductor. If we place the physically reasonable restriction on the configuration-interaction basis that only excitations between the highest (d-related) orbitals $t_2$ and e are allowed, we conclude that the results of both approaches are in excellent agreement.