One hole in a CuO2 plane: Resonating-valence-bond-like behavior

Although convincing arguments have been made which suggest that the three-band model of the high-T-c perovskite superconductors can be reduced to the single-band t-J model, there is a wealth of experimental data which indicates that this simplification may not be as valid as was first hoped. We perform variational and numerical calculations which demonstrate that in the absence of the Heisenberg interaction, the three-band model can provide a low-spin ground state, not the Nagaoka ferromagnetism predicted by the t model. We focus attention on the copper spin-spin correlations S-k and the oxygen hole occupation number N-k in order to provide evidence for or against long-range magnetic order and a Fermi discontinuity, respectively. The observed behavior appears similar to a Fermi liquid with a large Fermi surface, but there is no discontinuity in N-k, and the system is clearly dominated by quantum spin fluctuations. A tendency to form spin dimers is seen, providing evidence for a resonating valence bond ground state.