Quantum Monte Carlo study of the two-dimensional fermion Hubbard Model

TL;DR

This study uses large-scale determinant Quantum Monte Carlo simulations to analyze the electronic and magnetic properties of the two-dimensional fermion Hubbard model at half-filling, revealing how correlations affect the Fermi surface and antiferromagnetic order.

Contribution

It provides detailed, large-scale quantum Monte Carlo data on the Hubbard model, including effective bandwidth, momentum distribution, and magnetic correlations, with improved resolution for experimental comparison.

Findings

Correlations broaden the Fermi surface but preserve signatures near Brillouin zone edges.

Antiferromagnetic order parameter evolves from weak to strong coupling.

Enhanced momentum-space Green's function resolution aids experimental comparison.

Abstract

We report large scale determinant Quantum Monte Carlo calculations of the effective bandwidth, momentum distribution, and magnetic correlations of the square lattice fermion Hubbard Hamiltonian at half-filling. The sharp Fermi surface of the non-interacting limit is significantly broadened by the electronic correlations, but retains signatures of the approach to the edges of the first Brillouin zone as the density increases. Finite size scaling of simulations on large lattices allows us to extract the interaction dependence of the antiferromagnetic order parameter, exhibiting its evolution from weak coupling to the strong coupling Heisenberg limit. Our lattices provide improved resolution of the Green's function in momentum space, allowing a more quantitative comparison with time-of-flight optical lattice experiments.