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All instances / Hubbard

Hubbard square 16x16, open, U = 8, n = 0.875

Record

-0.7288 E/site

Fixed-node GFMC (trial state: ACE)

Gu et al. (2026) · lowest unflagged energy published, a projected estimate (rules §6)

The Hamiltonian

H = −t ∑⟨ij⟩,σ (c†iσcjσ + h.c.) + U ∑i ni↑ni↓

t = 1, U = 8, N↑ = N↓ = 112 on 256 sites.

lattice
square
sites
256
boundary
open
Nf
112
U
8
energies
4

Stored as a total energy; quoted here as E/site, which is what the papers report (how the conversion works).

Every published energy

Grouped by what the number is. On a solved instance the exact energy is the record; otherwise the lowest unflagged energy of any group holds it (rules §6).

Strict variational upper bounds (2)

Energies that a variational state reached (VMC, DMRG and MPS at finite bond dimension, PEPS, NQS, VQE). Each is an upper bound on the ground-state energy.

E/sitedistance to recordσVar(E)V-score methodsourceyear
-0.728 8.0e-4 n/a n/a n/a ACE (16 conv layers)
peer reviewed
Gu et al. (2026) 2026
-0.7236 5.2e-3 n/a n/a n/a SCALE (1 conv layer)
peer reviewed
Gu et al. (2026) 2026

Projected or fixed-node estimates (2)

Variational only within a constraint: fixed-node, constrained-path, GFMC on a trial state. Each depends on its node or constraint, so two of them are not cleanly comparable to each other or to strict bounds.

E/sitedistance to recordσVar(E)V-score methodsourceyear
-0.7288record 0 n/a n/a n/a Fixed-node GFMC (trial state: ACE)
peer reviewed
Gu et al. (2026) 2026
-0.7267 2.1e-3 n/a n/a n/a Fixed-node GFMC (trial state: SCALE, 1 conv layer)
peer reviewed
Gu et al. (2026) 2026

How these numbers were read

Where each number below was read, and how it was checked.

-0.7288, Fixed-node GFMC (trial state: ACE)

Checked 2026-10-22 · source text of arXiv:2604.25775 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; single reading

Reported as. -0.7288

Table I (16x16 Hubbard, U=8 and delta=1/8 per Sec. III C text; caption prints neither); columns t'=0 OBC | t'=0 PBC | t'=-0.2 PBC; row ACE+GFMC, column t'=0 OBC; sources/2604.25775.txt line 481; version read: arXiv v1 (sources/2604.25775.txt); APS copy not reached (403, 2026-10-16) | Eq. (8): H = -t sum_<ij> - t' sum_<<ij>> + U sum n_up n_dn, t = 1, U = 8, doping 1/8 (Sec. III), periodic unless the column says OBC; energies per site. Pinning fields only in pre-training (App. C).

-0.728, ACE (16 conv layers)

Checked 2026-10-22 · source text of arXiv:2604.25775 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; single reading

Reported as. -0.7280

Table I (16x16 Hubbard, U=8 and delta=1/8 per Sec. III C text; caption prints neither); columns t'=0 OBC | t'=0 PBC | t'=-0.2 PBC; row ACE, column t'=0 OBC; sources/2604.25775.txt line 480; version read: arXiv v1 (sources/2604.25775.txt); APS copy not reached (403, 2026-10-16) | Eq. (8): H = -t sum_<ij> - t' sum_<<ij>> + U sum n_up n_dn, t = 1, U = 8, doping 1/8 (Sec. III), periodic unless the column says OBC; energies per site. Pinning fields only in pre-training (App. C).

-0.7267, Fixed-node GFMC (trial state: SCALE, 1 conv layer)

Checked 2026-10-22 · source text of arXiv:2604.25775 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; single reading

Reported as. -0.7267

Table I (16x16 Hubbard, U=8 and delta=1/8 per Sec. III C text; caption prints neither); columns t'=0 OBC | t'=0 PBC | t'=-0.2 PBC; row SCALE+GFMC, column t'=0 OBC; sources/2604.25775.txt line 479; version read: arXiv v1 (sources/2604.25775.txt); APS copy not reached (403, 2026-10-16) | Eq. (8): H = -t sum_<ij> - t' sum_<<ij>> + U sum n_up n_dn, t = 1, U = 8, doping 1/8 (Sec. III), periodic unless the column says OBC; energies per site. Pinning fields only in pre-training (App. C).

-0.7236, SCALE (1 conv layer)

Checked 2026-10-22 · source text of arXiv:2604.25775 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; single reading

Reported as. -0.7236

Table I (16x16 Hubbard, U=8 and delta=1/8 per Sec. III C text; caption prints neither); columns t'=0 OBC | t'=0 PBC | t'=-0.2 PBC; row SCALE, column t'=0 OBC; sources/2604.25775.txt line 478; version read: arXiv v1 (sources/2604.25775.txt); APS copy not reached (403, 2026-10-16) | Eq. (8): H = -t sum_<ij> - t' sum_<<ij>> + U sum n_up n_dn, t = 1, U = 8, doping 1/8 (Sec. III), periodic unless the column says OBC; energies per site. Pinning fields only in pre-training (App. C).

Coverage

Newest published number here: 2026.

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