Electronic band structure of CaBi sub 2 Sr sub 2 Cu sub 2 O sub 8.

The band structure for body-centered-tetragonal Ca sub 2 Bi sub 2 Sr sub 2 Cu sub 2 O sub 8 has been calculated in the local-density-functional approach using the linearized muffin- tin-orbital method with the atomic-sphere approximation. This is the undistorted, stoichiometric parent compound to the recently reported 84K superconductor. The main band features at the Fermi level include a pair of nearly half-filled two-dimensional Cu-O 3d-2p bands similar to those found in the previous Cu- O planar superconductors as well as a pair of slightly- filled Bi 6p bands that provide additional carriers in the Bi-O planes.