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 much greater than U, U similar to t at quarter filling, where previous studies suggested the possibility of dominant superconducting pairing fluctuations before phase separation at a critical value V V-PS. We calculate V-PS and the Luttinger Liquid correlation exponent K-rho using quantum Monte Carlo and exact diagonalization methods. Our results for U = t and n = 1/2 show no superconductivity before phase separation.