Pairing Correlations in the Two-Dimensional Hubbard Model

TL;DR

This study uses quantum Monte Carlo methods to analyze pairing correlations in the 2D Hubbard model, revealing how these correlations vary with system size and interaction strength, and highlighting the dominance of d-wave pairing at weak coupling.

Contribution

It provides new computational insights into the behavior of pairing correlations in the 2D Hubbard model using the constrained-path quantum Monte Carlo method.

Findings

d_{x^2-y^2} pairing correlations are stronger than extended s at weak interactions

Long-range correlations diminish with increasing system size or interaction strength

d-wave pairing correlations are positive beyond several lattice constants at weak coupling

Abstract

We present the results of a quantum Monte Carlo study of the extended $s$ and the $d_{x^2-y^2}$ pairing correlation functions for the two-dimensional Hubbard model, computed with the constrained-path method. For small lattice sizes and weak interactions, we find that the $d_{x^2-y^2}$ pairing correlations are stronger than the extended $s$ pairing correlations and are positive when the pair separation exceeds several lattice constants. As the system size or the interaction strength increases, the magnitude of the long-range part of both correlation functions vanishes.