Structural and electronic properties of Hg1-yMoyBa2CuO4+δ

We discuss the effect of experimentally relevant defects on the structural and electronic properties of HgBa2CuO4+δ, using the full-potential linearized-augmented-plane-waves method, within the local-density approximation to density-functional theory. In particular, we study interstitial O and F atoms (δ= 0.5), and the 50% substitution of Hg atoms with Mo. We perform structural optimization, and obtain a good agreement with the experimental results and with their trends in terms of doping. Mo forms strong bonds with nearby apical oxygen atoms, bringing about large changes in both structural and electronic properties. The filling of the relevant Cu-O bands is increased (decrease of doping), consistently with the high Tc≈40 K experimentally found with δ≈0.5. O and F atoms are found to provide a remarkably similar band structure near EF, as far as the shape and the filling of the relevant Cu-O bands are concerned. This confirms an anomalous contribution of interstitial O to the doping.