Fermiology of cuprates from first principles: From small pockets to the Luttinger Fermi surface

Fermiology, the shape and size of the Fermi surface, underpins the low-temperature physical properties of a metal. Recent investigations of the Fermi surface of high-T(c) superconductors, however, show a most unusual behavior: upon addition of carriers, Fermi pockets appear around nodal (hole doping) and antinodal (electron doping) regions of the Brillouin zone in the pseudogap state. With progressive doping, delta, these evolve into well-defined Fermi surfaces around optimal doping (delta(opt)), with no pseudogap. Correspondingly, various physical responses, including d-wave superconductivity, evolve from highly anomalous up to delta(opt), to more conventional beyond. Describing this evolution holds the key to understanding high-temperature superconductivity. Here, we present ab initio quantum chemical results for cuprates, in an attempt to provide a quantitative description of the evolution of the Fermi surface with delta. Our results constitute an ab initio justification for several hitherto proposed semiphenomenological theories, offering a unified basis for understanding of various unusual physical responses of cuprates.