Charge distribution and electric-field gradients in YBa2Cu3O7-x.

摘要: The electric-field gradients (EFG's) of YBa{sub 2}Cu{sub 3}O{sub 7}, 6.5}, and 6} are calculated on a first-principles basis using the full-potential linear augmented-plane-wave (LAPW) method in which exchange correlation effects treated by local-density approximation (LDA). Good agreement with experimental EFG's their anisotropies is found for Cu(1) position all three compounds. For 7} same true oxygen positions, while at Cu(2) direction EFG predicted correctly, but transfer 0.07 electrons from {ital d}{sub x}{sup 2}{minus}{ital y}{sup 2}} to z}{sup symmetry would be needed bring theoretical into value. calculations 6.5} (assuming an ordered structure threefold coordinated oxygens) confirm assignment strengthen confidence our results. origin discussed relation anisotropy electronic charge distribution illustrated connection symmetry-decomposed partial charges difference-electron-density maps. It shown that LDA yield reliable distributions themore » so sensitive.« less