QMBLthe quantum many-body leaderboard

All instances / Hubbard

Hubbard rectangular 6x48, U = 8, n ≈ 0.9167

Best values (rules §6)

best variational -0.67269(3) VMC (Jastrow + BF)
Wu et al. (2024) · the lowest unflagged variational energy, a strict variational bound
best projected -0.6862(2) CP-AFQMC (stripe)
Xu et al. (2022) · the lowest unflagged projected energy, a projected estimate, which depends on its node or constraint

Energies as E/site. Classes are different claims and are not ranked against each other.

The Hamiltonian

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

t = 1, U = 8, N↑ = N↓ = 132 on 288 sites.

lattice
rectangular-6x48
sites
288
boundary
periodic
Nf
132
U
8
energies
7

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. The exact energy comes first where there is one; in every other group the lowest unflagged energy is its best value, and each row's distance is to that best (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 class bestσVar(E)V-score methodsourcecodeyearcomment
-0.67269best variational 0 3.1e-5 1.91e+1 1.1e-2 VMC (Jastrow + BF)
VarBench reference run
Wu et al. (2024) run script 2024
-0.66615 6.5e-3 3.5e-5 2.32e+1 1.3e-2 VMC (Jastrow + BF)
VarBench reference run
Wu et al. (2024) run script 2024

Projected or fixed-node estimates (5)

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 class bestσVar(E)V-score methodsourcecodeyearcomment
-0.6862best projected 0 2.0e-4 n/a n/a CP-AFQMC (stripe)
peer reviewed
Xu et al. (2022) 2022
-0.6855tied with best projected at 2σ 7.0e-4 2.0e-4 n/a n/a CP-AFQMC (stripe)
peer reviewed
Xu et al. (2022) 2022
-0.6820 4.2e-3 2.0e-4 n/a n/a CP-AFQMC (stripe)
peer reviewed
Xu et al. (2022) 2022
-0.67820 8.0e-3 3.1e-5 n/a n/a FN-GFMC (Jastrow + BF)
VarBench reference run
Wu et al. (2024) run script 2024
-0.67309 1.3e-2 3.5e-5 n/a n/a FN-GFMC (Jastrow + BF)
VarBench reference run
Wu et al. (2024) run script 2024

How these numbers were read

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

-0.6862(2), CP-AFQMC (stripe)

Checked 2026-10-07 · source text of arXiv:2112.02187 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. -0.6862(2)

Table II, row 48 x 6, column λ = 8 (2/3-filled stripe state); mixed-estimator constrained-path AFQMC, not a variational bound | Energy per site in units of t, U = 8, hole doping 1/12, 'fully periodic supercells ... with no pinning fields' (Table II caption); 48 x 6 is QMBL's 6 x 48 torus with 132 + 132 electrons.

-0.6855(2), CP-AFQMC (stripe)

Checked 2026-10-07 · source text of arXiv:2112.02187 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. -0.6855(2)

Table II, row 48 x 6, column λ = 12 (filled stripe state); mixed-estimator constrained-path AFQMC, not a variational bound | Energy per site in units of t, U = 8, hole doping 1/12, 'fully periodic supercells ... with no pinning fields' (Table II caption); 48 x 6 is QMBL's 6 x 48 torus with 132 + 132 electrons.

-0.6820(2), CP-AFQMC (stripe)

Checked 2026-10-07 · source text of arXiv:2112.02187 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. -0.6820(2)

Table II, row 48 x 6, column λ = 6 (half-filled stripe state); mixed-estimator constrained-path AFQMC, not a variational bound | Energy per site in units of t, U = 8, hole doping 1/12, 'fully periodic supercells ... with no pinning fields' (Table II caption); 48 x 6 is QMBL's 6 x 48 torus with 132 + 132 electrons.

-0.67820(3), FN-GFMC (Jastrow + BF)

Checked 2026-09-29 · run script scripts/Hubbard/rectangular-6x48_288_P_132_8/FN-stripes/fn_hubbard.sh with datprep.d and datasfn.d, programs/vmc_hubbard/{Prep_stripes_wf.f, Main_stripes_wf.f, Energy.f90, Variance.f} read (varbench/methods@ed31bb0); VarBench history (git clone of github.com/varbench/varbench, partial, read with git log --follow; old names normalised)

Reported as. -195.322 | 0.009 | (VarBench upload by L. F. Tocchio)

48 x 6 torus (the compiled nx = 48, nh = 288; ny = nh/nx = 6), periodic in both directions, t = 1, no t', U = 8 with U n_up n_dn (no constant shift: the diagonal energy is U per doubly occupied site, Main_*_wf.f 'diag(k)=diag(k)-U'), N_up = nelup = 132, N_dn = 288 - neldo = 132 (particle-hole transformed down spins, as the code states for iopt >= 0): the instance. Stripe wavelength 8 as printed. Lattice fixed-node GFMC (gamma = 0) on the VMC state: projected is right; its trial energy etry agrees with the result per site. The M3 flag (FN below the best variational bound) is expected: FN improves on its own trial state. No output log in the repository (scope config). FN not printed in the papers.

-0.67269(3), VMC (Jastrow + BF)

Checked 2026-09-29 · run script scripts/Hubbard/rectangular-6x48_288_P_132_8/VMC-stripes/vmc_hubbard.sh with datprep.d and datasvmc.d, programs/vmc_hubbard/{Prep_stripes_wf.f, Main_stripes_wf.f, Energy.f90, Variance.f} read (varbench/methods@ed31bb0); VarBench history (git clone of github.com/varbench/varbench, partial, read with git log --follow; old names normalised)

Reported as. -193.735 | 0.009 | 19.1 (VarBench upload by L. F. Tocchio)

48 x 6 torus (the compiled nx = 48, nh = 288; ny = nh/nx = 6), periodic in both directions, t = 1, no t', U = 8 with U n_up n_dn (no constant shift: the diagonal energy is U per doubly occupied site, Main_*_wf.f 'diag(k)=diag(k)-U'), N_up = nelup = 132, N_dn = 288 - neldo = 132 (particle-hole transformed down spins, as the code states for iopt >= 0): the instance. Stripe wavelength 8 as printed. Jastrow + backflow VMC: variational is right. The M11 margins over the uniform state are the physics of the stripe state, not an error. No output log in the repository (scope config). Published corroboration: arXiv:1905.02658v2 Table 1, p = 12: '-0.6726(1) (λ = 8)' (size-averaged), stored -0.67269.

Coverage

Newest published number here: 2024.

This instance as data

JSON · source file on GitHub · add a result · open an issue about this instance