A strongly correlated Hubbard (t-t′-U) model is studied using a variational Monte Carlo method. The magnitude of momentum distribution function n(k) varies slightly near the nodal quasi-Fermi surface [∼(π/2,π/2)], but varies outstandingly in an antinodal part [near (π,0)], as the value of t′/t varies, which is sensitive to the strength of superconductivity. Furthermore, the behavior of the slope of n(k) around (π,0) coincides well with that of the d-wave superconducting correlation function. It follows the electrons near the antinode play a leading role to control the strength of superconductivity.
- Fermi surface
- Van Hove singularity