Atomistic computer simulation techniques were used to investigate the defect and ion transport properties of this superconductor. Its tetragonal structure was correctly reproduced by using the present potential model. The defect calculations predicted that the most favorable O interstitial position was the O(4) [½½0] site on the Hg plane; in agreement with diffraction studies. It was found that there was significant local relaxation around this defect. A complex defect which involved the substitution of Cu for Hg was also examined. Exothermic energies were predicted for the hole-doping (oxidation) reaction in which an O excess was incorporated as doubly-charged O(4) interstitials, and compensated by hole formation. The diffusion of O was attributed to interstitial migration, and was predicted to be both rapid and anisotropic.

M.S.Islam, L.J.Winch: Physical Review B, 1995, 52[14], 10510-5