Density functional studies of muonium in nitrogen-aggregate containing diamond: the Mu_X centre.

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 CVD diamond, and muonium, via μSR, can provide useful characterisation 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.