ELECTRONIC BAND-STRUCTURE OF YBA2CU3O7 AND YBA2CU3O6 BY DENSITY FUNCTIONAL PSEUDOPOTENTIAL METHOD

The electronic structure of the high-T(c) superconductor YBa2Cu3O7 and its parent material YBa2Cu3O6 is investigated using the density functional pseudopotential approach. A mixed-basis formalism is newly developed to efficiently represent the highly localized copper 3d states. Application of this method to YBa2Cu3O7 yields an electronic structure different from previous results via the LAPW and LMTO methods, especially near the Fermi level. The probability amplitude above the Fermi level in YBa2Cu3O7 is distributed mainly in the CuO2 plane and has a dp-sigma* character with some dp-pi* components. Hole concentration in the CuO2 plane of YBa2CuO7 is estimated to be 0.14 per Cu atom.