Electronic band structure of YBa 2Cu 3O 7 and YBa 2Cu 3O 6 by density functional pseudopotential method

Abstract

The electronic structure of the high- T c superconductor YBa 2Cu 3O 7 and its parent material YBa 2Cu 3O 6 is investigated usi ng 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 YBa 2Cu 3O 7 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 YBa 2Cu 3O 7 is distributed mainly in the CuO 2 plane and has a dpσ ∗ character with some dpπ ∗ components. Hole concentration in the CuO 2 plane of YBa 2Cu 3O 7 is estimated to be 0.14 per Cu atom.