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Hubbard rectangular 4x16, U = 8, n = 0.875

Hubbard/rectangular-4x16_64_P_28_8

Record

-0.76623(1) E/site

ACE (16 conv layers) + full symmetry projection

Gu et al. (2026) · lowest eligible strict variational bound (rules §6)

The Hamiltonian

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

t = 1, U = 8, N = N = 28 on 64 sites.

lattice
rectangular-4x16
sites
64
boundary
periodic
Nf
28
U
8
energies
8

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

Every published energy

Grouped by what the number is. Ranking happens only inside the first group.

Strict variational upper bounds (7)

The record is the lowest eligible energy in this group, and only this group.

E/siteσVar(E)V-score methodsourceyear
-0.76623(1)record 1.0e-5 n/a n/a ACE (16 conv layers) + full symmetry projection
preprint
Gu et al. (2026) 2026
-0.76560(1) 1.0e-5 n/a n/a NNBF, 32 determinants + free projection to the fully symmetric state
preprint
Loehr & Clark (2025) 2025
-0.76486(2) 2.0e-5 n/a n/a NNBF, symmetry optimization with 32 determinants
preprint
Loehr & Clark (2025) 2025
-0.76464(1) 1.0e-5 n/a n/a ACE (16 conv layers), no explicit symmetry
preprint
Gu et al. (2026) 2026
-0.76413(3) 3.0e-5 2.00e+0 5.2e-3 HFPS (hidden-fermion Pfaffian state)
peer reviewed
Chen et al. (2025) 2025
-0.7629800 n/a n/a n/a Transformer backflow + MARCH optimizer
peer reviewed ineligible: sampled, no error bar
Gu et al. (2025) 2025
-0.75300(5) 4.7e-5 4.40e-1 1.2e-3 VMC Hidden Fermion Determinant State Ansatz (N_hidden = 16. Single hidden layer fully connected net with alpha = 6). Soft mean-field constraint for lambda = 8 stripe order. Moreno et al. (2022) 2022

Projected or fixed-node estimates (1)

Variational only within a constraint: fixed-node, constrained-path, GFMC on a trial state. Node- or constraint-dependent, so not cleanly comparable to each other or to the group above, and never the record.

E/siteσVar(E)V-score methodsourceyear
-0.76647(2) 2.0e-5 n/a n/a ACE (16 conv layers) trial state + fixed-node GFMC
preprint
Gu et al. (2026) 2026

How these numbers were read

Rows added after the VarBench import record where the number came from.

-0.76647(2) — ACE (16 conv layers) trial state + fixed-node GFMC

Checked 2026-09-10 · source text/table parsed locally (arXiv HTML or pypdf), no LLM transcription

Reported as. -0.76647 (+/- 0.00002) per site

Sec. III.3.1: "a GFMC calculation with the ACE trial wave-function gives an even lower energy of -0.76647(2)". Fixed-node: upper bound but node-dependent.

-0.76623(1) — ACE (16 conv layers) + full symmetry projection

Checked 2026-09-10 · source text/table parsed locally (arXiv HTML or pypdf), no LLM transcription

Reported as. -0.76623 (+/- 0.00001) per site

Sec. III.3.1: "reach a new state-of-the-art energy of -0.76623(1)".

-0.76560(1) — NNBF, 32 determinants + free projection to the fully...

Checked 2026-09-10 · source text/table parsed locally (arXiv HTML or pypdf), no LLM transcription

Reported as. -0.7656 (+/- 0.00001) per site

Sec. III: "further projected at essentially no cost to the fully symmetric state to reach an energy of -0.76560(1)". This is the best 4x16 number in arXiv:2510.26906v1.

-0.76486(2) — NNBF, symmetry optimization with 32 determinants

Checked 2026-09-10 · source text/table parsed locally (arXiv HTML or pypdf), no LLM transcription

Reported as. -0.76486 (+/- 0.00002) per site

Same section, before the free projection.

-0.76464(1) — ACE (16 conv layers), no explicit symmetry

Checked 2026-09-10 · source text/table parsed locally (arXiv HTML or pypdf), no LLM transcription

Reported as. -0.76464 (+/- 0.00001) per site

Sec. III.3.1: "achieves a ground-state energy of -0.76464(1)".

-0.76413(3) — HFPS (hidden-fermion Pfaffian state)

Checked 2026-09-13 · arXiv HTML parsed locally, no LLM transcription

Reported as. -0.76413 (+/- 0.00003) per site

Sec. III: "The energy we obtain in the 16x4 lattice is E/N = -0.76413, outperforming a recent result E/N = -0.76298 produced by Transformer-NNBF". Instance identity confirmed by that comparison value; the number is independently quoted as the HFPS result by both arXiv:2604.25775 and arXiv:2510.26906. No error bar in Sec. III; Table IV of the same paper (raw data of Fig. 7, L x 4 PBC lattices, 1/8 doping, U = 8) gives -0.76413(3) and sigma^2/N_site = 0.031283, added 2026-09-15. Published as PNAS 123, e2535288123 (2026); read from the arXiv version, the journal version not compared.

-0.7629800 ○ — Transformer backflow + MARCH optimizer

Checked 2026-09-10 · source text/table parsed locally (arXiv HTML or pypdf), no LLM transcription

Reported as. -0.76298 per site

Supp. Sec. 4.1: "our NQS yields a ground state energy of -0.76298" on 16x4 PBC. Instance identity confirmed: same passage quotes HFDS -0.753(2), matching the VarBench row -0.753000(47). No error bar given.

Coverage

Newest published number here: 2026. 7 rows added from the 2026-09 literature sweep, on top of the VarBench snapshot of 2024-10-22.

This instance as data

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