d-Wave Pairing in the Presence of Long-Range Coulomb Interactions

The one-band extended Hubbard model in two dimensions near band-filling 1/2 is solved in the fluctuation exchange approximation, including the long-range (1/r) part of the Coulomb interaction, up to 4th neighbor distance. Our results suggest that d_(x^2 - y^2) pairing in the Hubbard model is robust against the inclusion of long-range Coulomb interactions with moderate 1st neighbor repulsion strength V_1. d_(x^2 - y^2) pairing is suppressed only at large V_1 (>~ 0.25U-0.4U), due to incipient charge density wave instabilities.