Indications for RVB superconductivity in a generalized t-J model for the cuprates

We evaluate numerically several superconducting correlation functions in a generalized t-J model derived for hole-doped CuO2 planes. The model includes a three-site term t '' similar to that obtained in the large-U limit of the Hubbard model but of opposite sign for realistic O-O hopping. For parameters close to realistic values, we obtain strong evidence of superconductivity of predominantly d(x2-y2) character. The ground state has a large overlap with a very simple resonating-valence-bond (RVB) wave function with off-diagonal long-range order. This function reproduces the main features of the magnetic and superconducting correlation functions.