Absence of superconductivity in the 1d extended hubbard model with repulsive interactions

We investigate numerically the ground state of the 1D extended Hubbard model, with on-site interaction U and nearest-neighbor interaction V. We focus V U, U ~ t at quarter filling, where previous studies suggested the possibility of dominant superconducting pairing fluctuations before phase separation at a critical value V = vps. We calculate vps and the Luttinger Liquid correlation exponent Kρ using quantum Monte Carlo and exact diagonalization methods. Our results for U = t and n = 1/2 show no superconductivity before phase separation.