The detection of quantum oscillations in the electrical resistivity of
YBa2Cu3O6.5 provides direct evidence for the existence of Fermi surface pockets
in an underdoped cuprate. We present a theoretical study of the electronic
structure of YBa2Cu3O7-d (YBCO) aiming at establishing the nature of these
Fermi pockets, i.e. CuO2 plane versus CuO chain or BaO. We argue that electron
correlation effects, such as orbital-dependent band distortions and highly
anisotropic self-energy corrections, must be taken into account in order to
properly interpret the quantum oscillation experiments.Comment: A high-resolution version can be found at
http://www.physics.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Articles/YBCO_OrthoII_LDA.pd