Construction of model Hamiltonians for transition-metal impurities via the quasiparticle self-consistent GW method

We show a method to construct model Hamiltonians for describing multiplet excitations of transition-metal impurities. Here, we treat systems of a transition metal substituting Al in & alpha;-Al2O3. Based on the results of quasiparticle self-consistent GW (QSGW) calculations for the systems, we construct the model Hamiltonian of 3d orbitals. We determine not only the crystal-field parameters, but also the parameters of effective interactions based on the theoretical correspondence between the QSGW calculations and the model Hamiltonian, and investigate the systematic change in these parameters. Finally, we discuss the structures of multiplet excitations calculated from these parameters.