Precise band structure and Fermi-surface calculation for ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$: Importance of three-dimensional dispersion

With the appearance of angle-resolved photoemission data allowing the identification and measurement of the Fermi surface of the high-${\mathit{T}}_{\mathit{c}}$ cuprate superconductors, it is important to have precise local-density calculations with which to compare. We present well-converged local-density predictions of the band structure and Fermi surface of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$, giving special attention to the position of the flat Cu-O chain-derived bands and the effect of the buckling of the Cu-O chain that is predicted by total-energy calculations and that has been inferred by an x-ray-scattering study. We emphasize the c-axis dispersion that will lead to apparent broadening of the Fermi surface in experiments interpreted in terms of a two-dimensional electronic structure.