GROUP THEORETICAL IDENTIFICATION OF ACTIVE LOCALIZED ORBITAL SPACE INHIGH T-C CUPRATE SUPERCONDUCTORS

There is a widely shared consensus that the pair condensate wavefuncti on in cuprate superconductors has a dominant d(x)(-y)(2)(2) symmetry. In this paper a group theoretical analysis of the pair condensate wave function in real space for cuprate superconductors is presented. The a nalysis indicates that there is a degenerate pair of active bands in c uprate superconductors which are principally derived from localized e- orbitals and two possible singlet pair states formed from two differen t orbitals with symmetries a(1), b(1) or a(2), b(2) and all three may contribute to the condensate wavefunction. Hund's rule and the experim ental observation that singlet pairing with a short coherence length o ccurs in cuprate superconductors, indicates that the first option is t he most likely candidate in these materials and that hole doping mainl y occurs from B-1(1) pairs of e-orbitals giving rise to singlet electr on pairing and the phenomenon of high T-c cuprate superconductivity. ( C) 1998 Elsevier Science Ltd. All rights reserved.