QMBLthe quantum many-body leaderboardbeta

All instances / J1-J2

J1-J2 square 16x16, J2 = 0.48

No record

—

sampled rows carry no error bar (rules §6). Every row is still listed below.

The Hamiltonian

H = ∑⟨ij⟩ σi·σj + J2 ∑⟨⟨ij⟩⟩ σi·σj

J1 = 1, J2 = 0.48, nearest and next-nearest neighbours, written with Pauli matrices.

lattice
square
sites
256
boundary
periodic
J2
0.48
energies
3

Stored as a total energy in the convention of VarBench; quoted here as E/N (S.S), 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 (2)

Where the instance is not solved, the record is the lowest eligible energy in this group; where it is, the lowest eligible energy here is the best variational bound and the closest challenger to the exact one.

E/N (S.S)distance to recordσVar(E)V-score methodsourceyear
-0.5014700 n/a n/a n/a n/a CNN (CNN1, 1 Lanczos step)
peer reviewed ineligible: sampled, no error bar
Liang et al. (2023) 2023
-0.5012200 n/a n/a n/a n/a CNN
peer reviewed ineligible: sampled, no error bar
10.1109/TPDS.2022.3145163, 2022

Extrapolations (1)

Zero-variance, bond-dimension or Trotter-error extrapolations. Not a bound: no ansatz ever reached the number, so it cannot hold the record.

E/N (S.S)distance to recordσVar(E)V-score methodsourceyear
-0.5008 n/a 2.0e-4 n/a n/a TPS (extrapolated: χ → ∞ (contraction dimension Dc, linear in 1/Dc²))
peer reviewed
arXiv:1112.3331 2016

How these numbers were read

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

-0.5014700 — CNN (CNN1, 1 Lanczos step)

Checked 2026-10-07 · source text of arXiv:2204.07816 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. −0.501 47

Table 1 of the published article ('achieved by CNN1 with 106 529 parameters. The values are obtained by the Lanczos step with p = 1'), row 16 x 16, column 0.48; no error bar printed | Energy per site in S.S units on periodic lattices (abstract: 'rectangular lattices within periodic boundary conditions'); its 10x10 cells at J2 = 0.50 and 0.60 equal the rows QMBL already carries.

-0.5012200 — CNN

Checked 2026-10-07 · source text of arXiv:2108.13830 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. -0.50122

Table 4 ('Energies for varied J2/J1 && system scales'), row 16 x 16, column 0.48; no error bar printed | Energy per site in S.S units, periodic boundary conditions (text: 'periodic boundary condition'); the 10x10 and 16x16 cells at J2 = 0.50 equal the rows QMBL already carries from this table.

-0.5008(2) — TPS (extrapolated: χ → ∞ (contraction dimension Dc, linear...

Checked 2026-10-07 · source text of arXiv:1112.3331 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. -0.5008(2)

Table I, row J2 = 0.48, column L=16 | Energy per site in S.S units; the table's own L = 4 and L = 6 ED columns equal QMBL's exact rows. The finite-size values are extrapolated linearly in 1/Dc^2 (text), so they are not upper bounds.

Coverage

Newest published number here: 2023. 3 rows added from the 2026-09 literature sweep, on top of the VarBench snapshot of 2024-10-22.

This instance as data

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