DETAILS ON THE “LIMIT” MODEL OF CuO2 PLANES

Abstract

We discuss a limiting procedure for solving for the electronic states in the standard tight-binding model of electrons in a CuO 2 plane, in which all contributions O (t2/U) are retained while all higher order terms are rejected. This limiting process yields the exact results in strong coupling, and uncovers a variety of quasiparticles: fermions with and without dispersion, localized spin-1 triplets, their interactions, but no superconductivity. In this paper we fill in some minor details and give a lower bound to the ground state energy valid at all ratios of t/U. We discuss the dynamic process by which two triplets can annihilate, and show that their lifetime is inversely proportional to their energy.