QUASI-PARTICLE SPECTRA OF HIGH-TEMPERATURE SUPERCONDUCTORS

We present a semiphenomenological approach to calculating the quasipar ticle spectra of high-temperature superconductors (HTSC's). It is base d on a particularly efficient parametrisation of the effective electro n-electron interaction afforded by the density-functional theory for s uperconductors and a tight-binding linearized-muffin-tin-orbital schem e for solving the corresponding Kohn-Sham-Bogoliubov-de Gennes equatio ns. We illustrate the method by investigating a number of site and orb ital specific, but otherwise phenomenological, models of pairing in qu antitative detail and discuss the results using BCS-like theory and in sights to the HTSC band structures. We compare our results for the gap function on the Fermi surface with those deduced from photoemission e xperiments on single crystals of YBa2Cu3O7. We also compare our predic tions for the temperature dependence of the specific heat with measure ments and conclude, provisionally, that the dominant pairing interacti on operates between electrons of opposite spin, on nearest-neighbor Cu sites in d(x2-y2) orbitals. [S0163-1829(98)04426-4].