Structure of negatively charged muonium in n-type GaAs.
Muon level-crossing resonance and muon-spin-rotation measurements on heavily doped {ital n}-type GaAs:Si and GaAs:Te show that the majority of positive muons implanted at room temperature form an isolated diamagnetic muonium center located at a high-symmetry site with Ga neighbors along the {l_angle}111{r_angle} direction(s). These experiments, together with theoretical considerations, imply that negatively charged muonium is at or near the tetrahedral interstitial site with four Ga nearest-neighbor atoms. Except for zero-point energy differences, these results should model negatively charged isolated hydrogen in GaAs.
We present a computational study of 2$p$ core-level X-ray photoemission spectra of transition metal monoxides MO (M=Ni, Co, Mn) and sesquioxides M$_2$O$_3$ (M=V, Cr, Fe) using a theoretical framework based on the local-density approximation (LDA) $+$ dynamical mean-field theory (DMFT). We find a very good description of the fine spectral features, which improves considerably over the conventional cluster model. We analyze the role of the non-local screening and its relationship to the long-range magnetic order and the lattice geometry. Our results reveal the potential of the present method for the analysis and interpretation of the modern high-energy-resolution experiments.