G. Baskaran et al., SUPERCONDUCTING GAP NODAL SURFACE AND FERMI-SURFACE - THEIR PARTIAL OVERLAP IN CUPRATES, Modern physics letters B, 9(19), 1995, pp. 1243-1252
Electron correlation in cuprates leads to a global constraint Sigma(k)
Delta(k) = 0 on the gap function Delta(k), resulting in a gap nodal s
urface. We give numerical results and qualitative physical arguments s
upported by some experimental results to argue that correlations also
lead to a local constraint on charge fluctuations in k-space close to
the Fermi surface, which may result in a substantial overlap of the Fe
rmi surface with the gap nodal surface.