QMBLthe quantum many-body leaderboard

All instances / Hubbard

Hubbard rectangular 10x16, U = 8, n = 0.875, t12 (t2 = -0.2)

Record

-0.7434 E/site

Transformer backflow (MARCH)

Gu et al. (2026) · lowest unflagged energy published, a strict variational bound (rules §6)

The Hamiltonian

H = −t1 ∑⟨ij⟩,σ (c†iσcjσ + h.c.) −t2 ∑⟨⟨ij⟩⟩,σ (c†iσcjσ + h.c.) + U ∑i ni↑ni↓

t1 = 1, t2 = -0.2, U = 8, N↑ = N↓ = 70 on 160 sites.

This instance is a t12 variant with a next-nearest-neighbour hopping t2, written as in VarBench's Eq. (S6). t2 is the t′ of the sources' H = −t ∑⟨ij⟩ − t′ ∑⟨⟨ij⟩⟩ + U ∑ ni↑ni↓. The couplings are those each source prints (see the rows).

lattice
rectangular-10x16
sites
160
boundary
periodic
Nf
70
U
8
t1
1
t2
-0.2
energies
1

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 (1)

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
-0.7434record 0 n/a n/a n/a Transformer backflow (MARCH)
peer reviewed
Gu et al. (2026) 2026

How these numbers were read

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

-0.7434, Transformer backflow (MARCH)

Checked 2026-10-22 · source text of arXiv:2507.02644 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. −0.7434

Supplementary Table 5, row 16 × 10, t' = -0.2; dl/gu-si.txt line 200; no error bar | Energy per site in units of t. PBC per the Supplementary Table 5 caption ('Raw data for the energies of Hubbard model under PBC'); U = 8 and hole doping 1/8 per the main text (Fig. 4 caption: 'U = 8 and hole doping δ = 1/8 under PBC'; the t' = -0.2 study: 'Lx × 8 with Lx ranging from 8 to 32, with t' = -0.2 and δ = 1/8'). H has -t' sum_<<ij>>, so t2 = t'. The 16 x 4 and 16 x 16 values at t' = 0 equal the arXiv text's -0.76298 and -0.75630 to the printed digits. No error bar printed. Version read: journal Supplementary Information (41467_2026_74028_MOESM1_ESM.pdf); the arXiv text has no raw-data table.

Coverage

Newest published number here: 2026.

This instance as data

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