Quantum chemical formulation of high-T-C superconductivity

A detailed understanding of superconductivity in the cuprates is formulated . A cluster model is defined and evaluated by means of the regularized comp lete active space self-consistent field method. Signatures of local pair-br eaking excitations in a low-dispersive oxygen metal band, attenuated by the nearby buffer ions, and nonadiabatically spin-coupled to a disjoint antife rromagnetic band are quantified and proposed to be consistent with the spin -flip signature of high-ire superconductivity in YBa2Cu3O6+x. Critical prop erties of the scenario are (i) hole-clustering instabilities producing loca l angular (D-wave) and radial (S-wave) Cooper instabilities and (ii) nonadi abaticity between local hole cluster states and antiferromagnetism. The cup rates are said to belong to a class of superconductors for which the macros copic ground state is accessed by means of phase coherent hole cluster reso nances. This understanding is illustrated by a real-space BCS-like deductio n of the superconducting gap. A microscopic understanding of the order para meter symmetry emerges.