{
  "model": "Heisenberg",
  "lattice": "square",
  "n_sites": 38,
  "boundary": "P",
  "params": {},
  "instance_id": "Heisenberg/square_38_P",
  "rows": [
    {
      "energy": -103.04317,
      "sigma": null,
      "energy_variance": null,
      "dof": 38,
      "einf": 0,
      "v_score": null,
      "method": "ED",
      "ansatz": null,
      "method_detail": "",
      "method_as_published": "ED",
      "family": "other",
      "bound_type": "exact",
      "bound_type_reason": "numerically exact reference as stated by the source (assigned during source reading)",
      "reference": "Richter, Schulenburg & Honecker, Quantum magnetism in two dimensions: From semi-classical Néel order to magnetic disorder, in Quantum Magnetism, Lect. Notes Phys. 645, 85 (2004), arXiv:cond-mat/0412662, doi:10.1007/BFb0119592",
      "peer_reviewed": false,
      "source": "sweep-allresults-2026-10-24",
      "provenance": "primary",
      "verified": {
        "checked_on": "2026-10-24",
        "method": "arXiv:cond-mat/0412662: publisher PDF (Springer, scanned) Table 2.1, read from the page image rendered at 200 %; checked against the arXiv text (pypdf layout and plain modes); no LLM transcription of numbers; single reading + page-image check",
        "reported_as": "−25.7607925",
        "note": "Table 2.1 (p. 102), row N = 38, edge vectors (1, 7), (-5, 3), column E0. No other row on this cluster. | Spin-1/2 Heisenberg antiferromagnet H = J sum_<ij> S_i . S_j on the square lattice, J = 1, periodic boundaries on the finite lattice defined by the two edge vectors printed in the row (Betts construction, Sec. 2.4.1); E0 is the total singlet ground-state energy in S.S units, stored as the Pauli total 4 E0. Version read: publisher PDF (Springer, a scan), Table 2.1 on p. 102 read from the page image; identical to Table 1 of the arXiv text cond-mat/0412662. Peer review: a chapter of an edited lecture-notes volume, not a refereed journal.",
        "secondary_of": null
      },
      "precision": 3.9976e-7
    }
  ],
  "url": "https://qmbl.org/i/Heisenberg/square_38_P/",
  "per_site_divisor": 152,
  "per_site_label": "E/N (S.S)",
  "best": {
    "exact": {
      "energy": -103.04317,
      "sigma": null,
      "method": "ED",
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      "method_detail": "",
      "reference": "Richter, Schulenburg & Honecker, Quantum magnetism in two dimensions: From semi-classical Néel order to magnetic disorder, in Quantum Magnetism, Lect. Notes Phys. 645, 85 (2004), arXiv:cond-mat/0412662, doi:10.1007/BFb0119592",
      "bound_type": "exact",
      "energy_per_site": -0.6779155921052632
    },
    "variational": null,
    "projected": null,
    "extrapolated": null,
    "approximate": null,
    "below_exact": []
  },
  "no_best_reason": null,
  "record": {
    "energy": -103.04317,
    "sigma": null,
    "method": "ED",
    "ansatz": null,
    "method_detail": "",
    "reference": "Richter, Schulenburg & Honecker, Quantum magnetism in two dimensions: From semi-classical Néel order to magnetic disorder, in Quantum Magnetism, Lect. Notes Phys. 645, 85 (2004), arXiv:cond-mat/0412662, doi:10.1007/BFb0119592",
    "bound_type": "exact",
    "energy_per_site": -0.6779155921052632
  },
  "no_record_reason": null
}