Abstract
Diamond has potential as a wide band-gap semiconductor with high intrinsic carrier mobility, thermal conductivity and hardness. Hydrogen is involved in electrically active defects in chemical vapour deposited diamond, and muonium, via muon spin spectroscopy, can provide useful characterization for the configurations adopted by H atoms in a crystalline material. We present the results of a computational investigation into the structure of the Mu X centre proposed to be associated with nitrogen aggregates. We find that the propensity of hydrogen or muonium to chemically react with the lattice makes the correlation of Mu X with nitrogen aggregates problematic, and suggest alternative structures.