{
  "model": "ShastrySutherland",
  "lattice": "square",
  "n_sites": 36,
  "boundary": "P",
  "params": {
    "J": 0.5,
    "Jd": 1
  },
  "cluster": "6 x 6 square lattice with orthogonal dimers, periodic boundaries",
  "instance_id": "ShastrySutherland/square_36_P_J0.5_Jd1",
  "rows": [
    {
      "energy": -54,
      "sigma": null,
      "energy_variance": null,
      "dof": 36,
      "einf": 0,
      "v_score": null,
      "method": "ED",
      "ansatz": null,
      "method_detail": "Lanczos",
      "method_as_published": "exact diagonalisation (Lanczos)",
      "family": "other",
      "bound_type": "exact",
      "bound_type_reason": "numerically exact reference as stated by the source (assigned during source reading)",
      "reference": "Sindermann, Löw & Zittartz, Ground state properties of two spin models with exactly known ground states on the square lattice, Int. J. Mod. Phys. C 17, 1085 (2006), doi:10.1142/S0129183106009709, arXiv:cond-mat/0605464",
      "peer_reviewed": true,
      "source": "sweep-allresults-2026-10-20",
      "provenance": "primary",
      "verified": {
        "checked_on": "2026-10-20",
        "method": "source text of arXiv:cond-mat/0605464 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 (2026-10-20)",
        "reported_as": "-0.374999999999425",
        "note": "Table II (6 x 6), x = 0.5; version read: arXiv text (sources/cond-mat-0605464.txt); the journal version was not reached from this session, to be read on the verification pass (RULES.md 8) | Eq. (1) H = J2 sum S.S (square bonds) + J1 sum S.S (diagonal dimer bonds), x = J2/J1, E0/N per site in units of J1 (the Fig. 1 caption swaps the labels; the tables fix them: E0/N = -0.375, the dimer-product energy, for all x below xc, and x = 0.8 equals the 6 x 6 ED of arXiv:2311.16889).",
        "secondary_of": null
      },
      "corrections": [
        {
          "field": "energy",
          "to": -54,
          "reported_as": "-0.374999999999425 (E0/N, per site, units of J1 = Jd, S.S form)",
          "location": "Table II (N = 6 x 6 = 36, left half), row J2/J1 = 0.5 (arXiv:cond-mat/0605464)",
          "version_read": "recomputation (checks/exact-recompute-2026-10-families/); printed value read in arXiv:cond-mat/0605464v1 PDF, pypdf layout mode (shared cache sources/cond-mat-0605464v1.layout.txt), checked against the plain extraction, the project's sources/cond-mat-0605464.txt and a 110 dpi render of page 11; journal version (Int. J. Mod. Phys. C 17, 1085) not reached (HTTP 403)",
          "conversion": "18 dimers x (-3/4) = -13.5 in S units; x 4 = -54 (Pauli total)",
          "checked_on": "2026-10-24",
          "reason": "Rule for exact rows QMBL recomputed (2026-09-30; ruled for this row 2026-10-24): at J/Jd = 1/2 the dimer-singlet product state is a proven ground state (H splits into triangles h_t = (Jd/2) S1.S2 + J (S1.S3 + S2.S3), each bounded below by -3J/4 and saturated by the dimer state, also on the 6 x 6 torus), so E0 = -54 exactly (18 dimers x -3/4 x 4); the printed -0.374999999999425 per site carries the source's Lanczos residual (5.75e-13 per site). The row carries the exact value; the printed value stays here. See checks/exact-recompute-2026-10-families/.",
          "source_entry": "famE-exact-recompute#19, famP2-10-1142-s0129183106009709#11 (qmbl-verify 2026-10-23); rule for recomputed exact rows, 2026-09-30, ruled for these rows 2026-10-24",
          "from": -53.9999999999
        },
        {
          "field": "sampled",
          "to": false,
          "reported_as": "-0.374999999999425",
          "location": "arXiv:cond-mat/0605464 Table II (6 x 6), x = 0.5",
          "version_read": "the row's published method string (arXiv text, sources/cond-mat-0605464.txt)",
          "conversion": "none",
          "checked_on": "2026-10-25",
          "reason": "Deterministic: an exact (Lanczos) diagonalization carries no statistical error, but the label \"exact diagonalisation (Lanczos)\" matches none of isSampled's deterministic markers, so the row read as a sampled energy without an error bar; set as on the t-J Lanczos rows (ruled 2026-10-25).",
          "source_entry": "ruling of 2026-10-25 on the families port: sampled false on the cond-mat/0605464 exact rows",
          "from": true
        }
      ],
      "sampled": false
    }
  ],
  "url": "https://qmbl.org/i/ShastrySutherland/square_36_P_J0.5_Jd1/",
  "per_site_divisor": 144,
  "per_site_label": "E/N (S.S)",
  "best": {
    "exact": {
      "energy": -54,
      "sigma": null,
      "method": "ED",
      "ansatz": null,
      "method_detail": "Lanczos",
      "reference": "Sindermann, Löw & Zittartz, Ground state properties of two spin models with exactly known ground states on the square lattice, Int. J. Mod. Phys. C 17, 1085 (2006), doi:10.1142/S0129183106009709, arXiv:cond-mat/0605464",
      "bound_type": "exact",
      "energy_per_site": -0.375
    },
    "variational": null,
    "projected": null,
    "extrapolated": null,
    "approximate": null,
    "below_exact": []
  },
  "no_best_reason": null,
  "record": {
    "energy": -54,
    "sigma": null,
    "method": "ED",
    "ansatz": null,
    "method_detail": "Lanczos",
    "reference": "Sindermann, Löw & Zittartz, Ground state properties of two spin models with exactly known ground states on the square lattice, Int. J. Mod. Phys. C 17, 1085 (2006), doi:10.1142/S0129183106009709, arXiv:cond-mat/0605464",
    "bound_type": "exact",
    "energy_per_site": -0.375
  },
  "no_record_reason": null
}