QMBLthe quantum many-body leaderboard

All instances / t-J

t-J square, 26 sites, J = 0.5, 4 holes

Exact energy and best values (rules §6)

exact -0.7881242 ED
10.1103/PhysRevB.64.024512, · the instance is solved
best variational -0.7855(1) VMC (Gutzwiller)
10.1103/PhysRevB.64.024512, · the lowest unflagged variational energy, a strict variational bound
best projected -0.7841(1) FN-GFMC (Gutzwiller)
10.1103/PhysRevB.64.024512, · 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 P(c†iσcjσ + h.c.)P + J ∑⟨ij⟩ (Si·Sj − ninj/4)

t-J model: P projects out doubly occupied sites, S = σ/2. t = 1, J = 0.5; the exchange term includes −ninj/4. N↑ = 11, N↓ = 11 on 26 sites (4 holes). Cluster: square-shaped periodic cluster of 26 sites, edge vectors (5, 1) and (-1, 5), the only square-shaped cluster with N = 26 (RULES.md 2.1). Inferred, not printed: arXiv:cond-mat/0606659 describes its clusters as 'a square lattice with L sites and periodic boundary conditions rotated by 45 degrees such that L = 2l^2, l being an odd integer', which does not include L = 26, and states no other shape; arXiv:cond-mat/0009149 lists 13 shells for its 26-site cluster, as the (5, 1) cluster has (SWEEP.md, 2026-10-22). Confirmed by QMBL's diagonalization of the (5, 1) cluster (checks/tj-exact-recompute-2026-10/, 2026-10-23), which reproduces every printed 26-site exact energy to its printed digits: with 2 holes in all 14 momentum and C4 sectors, with 4 holes in the zero-momentum, C4-even sector, the lowest of the 1 to 6 of 14 sectors computed.

lattice
square
sites
26
boundary
periodic
t
1
J
0.5
N_up
11
N_dn
11
nn_term
true
energies
12

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).

Numerically exact (1)

Exact diagonalization, an exact solution, or sign-problem-free QMC where that is established. An exact energy is shown first, before the best of each other class. QMC is exact only within its error bar, which it must state, and reads exact (stochastic); an exact diagonalization outranks it. For a diagonalization resolved by symmetry sector only the ground state's sector is listed; the lowest energies of the other sectors are the instance's spectrum, in its JSON, and are not shown as the exact energy.

E/sitedistance to class bestσVar(E)V-score methodsourcecodeyearcomment
-0.7881242exact 0 n/a n/a n/a ED
quoted from another paper peer reviewed
10.1103/PhysRevB.64.024512, 2001

Strict variational upper bounds (6)

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
-0.7855best variational 0 1.0e-4 n/a n/a VMC (Gutzwiller)
peer reviewed
10.1103/PhysRevB.64.024512, 2001
-0.7852tied with best variational at 2σ 3.0e-4 1.0e-4 n/a n/a VMC (Gutzwiller)
peer reviewed
10.1103/PhysRevB.64.024512, 2001
-0.7812 4.3e-3 1.0e-4 n/a n/a VMC (Gutzwiller)
peer reviewed
10.1103/PhysRevB.64.024512, 2001
-0.76512 2.0e-2 1.0e-5 n/a n/a VMC (Pfaffian)
peer reviewed
10.1103/PhysRevB.74.165122, 2006
-0.7647 2.1e-2 1.0e-4 n/a n/a VMC (Gutzwiller)
peer reviewed
10.1103/PhysRevB.64.024512, 2001
-0.76461 2.1e-2 1.0e-5 n/a n/a VMC (RVB)
peer reviewed
10.1103/PhysRevB.74.165122, 2006

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
-0.7841best projected 0 1.0e-4 n/a n/a FN-GFMC (Gutzwiller)
peer reviewed
10.1103/PhysRevB.64.024512, 2001
-0.77770 6.4e-3 4.0e-5 n/a n/a FN-GFMC (Pfaffian)
peer reviewed
10.1103/PhysRevB.74.165122, 2006
-0.77595 8.1e-3 1.0e-5 n/a n/a FN-GFMC (Pfaffian)
peer reviewed
10.1103/PhysRevB.74.165122, 2006
-0.7759 8.2e-3 1.0e-4 n/a n/a FN-GFMC (Gutzwiller)
peer reviewed
10.1103/PhysRevB.64.024512, 2001
-0.77571 8.4e-3 1.0e-5 n/a n/a FN-GFMC (RVB)
peer reviewed
10.1103/PhysRevB.74.165122, 2006

How these numbers were read

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

-0.7881242, ED

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.78812

Table I, N = 22, L = 26, J/t = 0.5, column Exact; the acknowledgements (lines 829-831) credit D. Poilblanc's unpublished 26-site data (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.7855(1), VMC (Gutzwiller)

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.7855(1)

Table I, N = 22, L = 26, J/t = 0.5, column Best SR (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.7852(1), VMC (Gutzwiller)

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.7852(1)

Table I, N = 22, L = 26, J/t = 0.5, column VMC+2LS (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.7841(1), FN-GFMC (Gutzwiller)

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.7841(1)

Table I, N = 22, L = 26, J/t = 0.5, column VMC+LS+FN (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.7812(1), VMC (Gutzwiller)

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.7812(1)

Table I, N = 22, L = 26, J/t = 0.5, column VMC+LS (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.77770(4), FN-GFMC (Pfaffian)

Checked 2026-10-22 · source text of arXiv:cond-mat/0606659 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.77770(4)

Table II, J/t = 0.5, column Ẽ_Ψ0^γ=0 (Eq. 15, Pfaff) (line 395); version read: arXiv text (sources/cond-mat-0606659.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Eq. (1): H = -t sum (c+c + h.c.) + J sum (S_i.S_j - n_i n_j / 4), t = 1; Tables I and II print E/L, L = 26, for 2 and 4 holes. The Lanczos column agrees with the exact column of Sorella, Phys. Rev. B 64, 024512, Table I at J/t = 0.3, 0.5, 1.0 (4 holes), which fixes one convention for both papers (that paper is Sorella, Phys. Rev. B 64, 024512).

-0.77595(1), FN-GFMC (Pfaffian)

Checked 2026-10-22 · source text of arXiv:cond-mat/0606659 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.77595(1)

Table II, J/t = 0.5, column E_FN^Pfaff (line 395); version read: arXiv text (sources/cond-mat-0606659.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Eq. (1): H = -t sum (c+c + h.c.) + J sum (S_i.S_j - n_i n_j / 4), t = 1; Tables I and II print E/L, L = 26, for 2 and 4 holes. The Lanczos column agrees with the exact column of Sorella, Phys. Rev. B 64, 024512, Table I at J/t = 0.3, 0.5, 1.0 (4 holes), which fixes one convention for both papers (that paper is Sorella, Phys. Rev. B 64, 024512).

-0.7759(1), FN-GFMC (Gutzwiller)

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.7759(1)

Table I, N = 22, L = 26, J/t = 0.5, column VMC+FN (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.77571(1), FN-GFMC (RVB)

Checked 2026-10-22 · source text of arXiv:cond-mat/0606659 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.77571(1)

Table II, J/t = 0.5, column E_FN^RVB (line 395); version read: arXiv text (sources/cond-mat-0606659.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Eq. (1): H = -t sum (c+c + h.c.) + J sum (S_i.S_j - n_i n_j / 4), t = 1; Tables I and II print E/L, L = 26, for 2 and 4 holes. The Lanczos column agrees with the exact column of Sorella, Phys. Rev. B 64, 024512, Table I at J/t = 0.3, 0.5, 1.0 (4 holes), which fixes one convention for both papers (that paper is Sorella, Phys. Rev. B 64, 024512).

-0.76512(1), VMC (Pfaffian)

Checked 2026-10-22 · source text of arXiv:cond-mat/0606659 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.76512(1)

Table II, J/t = 0.5, column E_VMC^Pfaff (line 395); version read: arXiv text (sources/cond-mat-0606659.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Eq. (1): H = -t sum (c+c + h.c.) + J sum (S_i.S_j - n_i n_j / 4), t = 1; Tables I and II print E/L, L = 26, for 2 and 4 holes. The Lanczos column agrees with the exact column of Sorella, Phys. Rev. B 64, 024512, Table I at J/t = 0.3, 0.5, 1.0 (4 holes), which fixes one convention for both papers (that paper is Sorella, Phys. Rev. B 64, 024512).

-0.7647(1), VMC (Gutzwiller)

Checked 2026-10-22 · source text of arXiv:cond-mat/0009149 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.7647(1)

Table I, N = 22, L = 26, J/t = 0.5, column VMC (line 1051); version read: arXiv text (sources/cond-mat-0009149.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Table I: 'Energy per site in the t-J model', N electrons on L sites, t = 1. The Hamiltonian is not printed; its exact column on L = 26 (-0.64262, -0.78812, -1.17493) is the Lanczos column of Lugas, Spanu, Becca & Sorella, Phys. Rev. B 74, 165122, Table II, whose Eq. (1) includes -n_i n_j / 4 and periodic boundaries, so the 26-site rows share that instance.

-0.76461(1), VMC (RVB)

Checked 2026-10-22 · source text of arXiv:cond-mat/0606659 read locally (arXiv HTML or pypdf layout text); value copied from the harvested cell and the text, no LLM transcription of numbers; first reading and an adversarial second reading (2026-10-22)

Reported as. -0.76461(1)

Table II, J/t = 0.5, column E_VMC^RVB (line 395); version read: arXiv text (sources/cond-mat-0606659.txt); the journal version was not reached from this session (the publisher returned 403), to be read on the verification pass (RULES.md 8) | Eq. (1): H = -t sum (c+c + h.c.) + J sum (S_i.S_j - n_i n_j / 4), t = 1; Tables I and II print E/L, L = 26, for 2 and 4 holes. The Lanczos column agrees with the exact column of Sorella, Phys. Rev. B 64, 024512, Table I at J/t = 0.3, 0.5, 1.0 (4 holes), which fixes one convention for both papers (that paper is Sorella, Phys. Rev. B 64, 024512).

Coverage

Newest published number here: 2006.

This instance as data

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