Monte Carlo Diagonalization for Hubbard Model

Fuente: arXiv
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Auteurs principaux: Bernard, B., Charlebois, M.
Format: Preprint
Publié: 2025
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author Bernard, B.
Charlebois, M.
author_facet Bernard, B.
Charlebois, M.
contents The Hubbard model has often been studied with exact diagonalization (ED). This impurity solver is fundamentally limited by the exponential scaling of the Fock space. To address this problem, we introduce Monte Carlo diagonalization. Using a truncated Fock space constructed with a Monte Carlo approach, we reduce the size of the basis required to represent the Hamiltonian. We can then apply the Lanczos and band Lanczos algorithms in this truncated basis to find the ground state and the Green function. This results in a significant economy of resources and the capacity to break the $\sim$20-site limit of ED. Our results suggest that there is a threshold on the number of states needed to capture the physics. This allows us to reach clusters of size up to 32 sites and reproduce the expected physics.
format Preprint
id arxiv_https___arxiv_org_abs_2509_22975
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Monte Carlo Diagonalization for Hubbard Model
Bernard, B.
Charlebois, M.
Strongly Correlated Electrons
The Hubbard model has often been studied with exact diagonalization (ED). This impurity solver is fundamentally limited by the exponential scaling of the Fock space. To address this problem, we introduce Monte Carlo diagonalization. Using a truncated Fock space constructed with a Monte Carlo approach, we reduce the size of the basis required to represent the Hamiltonian. We can then apply the Lanczos and band Lanczos algorithms in this truncated basis to find the ground state and the Green function. This results in a significant economy of resources and the capacity to break the $\sim$20-site limit of ED. Our results suggest that there is a threshold on the number of states needed to capture the physics. This allows us to reach clusters of size up to 32 sites and reproduce the expected physics.
title Monte Carlo Diagonalization for Hubbard Model
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2509.22975