{
  "model": "Hubbard",
  "lattice": "chain",
  "n_sites": 14,
  "boundary": "P",
  "params": {
    "Nf": 4,
    "U": 4.64158883
  },
  "instance_id": "Hubbard/chain_14_P_4_4.64158883",
  "rows": [
    {
      "energy": -10.896957984833337,
      "sigma": null,
      "energy_variance": null,
      "dof": 8,
      "einf": 5.304672948571429,
      "v_score": null,
      "method": "ED",
      "method_detail": "",
      "method_as_published": "Exact diagonalization",
      "family": "other",
      "bound_type": "exact",
      "bound_type_reason": "exact diagonalization|ex",
      "reference": "[code](https://github.com/varbench/methods/blob/main/scripts/Hubbard/chain_14_P_4_4.64158882/ed_netket.sh)",
      "source": "varbench@2024-10-22",
      "provenance": "imported",
      "baseline": true,
      "verified": {
        "checked_on": "2026-09-16",
        "scope": "value",
        "method": "recomputed: Lanczos ED over the full fixed-(N_up, N_dn) space by two independent codes (checks/hubbard-u-labels/)",
        "location": "checks/hubbard-u-labels/",
        "reported_as": "-10.896957984833353 (ed_check.py) | -10.896957984834266 (ed_lib.mjs)",
        "conversion": "none",
        "note": "Reproduced at the grid U the instance now carries, not at the U of VarBench's name (relabels.mjs).",
        "source_entry": "B2-baseline-hubbard and E1-exact-recompute (qmbl-verify 2026-09-16)",
        "secondary_of": null
      }
    },
    {
      "energy": -10.896957987,
      "sigma": null,
      "energy_variance": 8.2e-12,
      "dof": 8,
      "einf": 5.304672948571429,
      "v_score": 2.4991157380644516e-13,
      "method": "DMRG",
      "method_detail": "bond dimension ~1500",
      "method_as_published": "DMRG (MaxBondDim ~1500)",
      "family": "tensor network",
      "bound_type": "variational",
      "bound_type_reason": "vmc|\\brbm\\b|\\brnn\\b|jast",
      "reference": "[code](https://github.com/varbench/methods/blob/main/programs/dmrg_itensors_hubbard/chain_14_P_4_4.64158882.jl)",
      "source": "varbench@2024-10-22",
      "provenance": "imported",
      "baseline": true
    }
  ],
  "coverage": [
    {
      "checked_on": "2026-09-15",
      "method": "table harvest of cached arXiv sources (match_tables.mjs --all), every matched paper read for this instance",
      "screened": [
        "arXiv:2502.17144"
      ],
      "found": 0,
      "note": "Only papers whose tables matched the instance by size were read; not a citation screen."
    }
  ],
  "relabelled": {
    "from": "Hubbard/chain_14_P_4_4.64158882",
    "checked_on": "2026-09-16",
    "reason": "The name's 4.64158882 misrounds the coupling of this Hamiltonian, 4.6415888336 (10^(6/9)). The exact diagonalization, -10.896957984833337, is the ground state at U = 4.64158883 and 3.03e-9 above the ground state at 4.64158882.",
    "evidence": "checks/hubbard-u-labels/"
  },
  "url": "https://qmbl.org/i/Hubbard/chain_14_P_4_4.64158883/",
  "per_site_divisor": 14,
  "per_site_label": "E/site",
  "record": {
    "energy": -10.896957984833337,
    "sigma": null,
    "method": "ED",
    "method_detail": "",
    "reference": "[code](https://github.com/varbench/methods/blob/main/scripts/Hubbard/chain_14_P_4_4.64158882/ed_netket.sh)",
    "bound_type": "exact",
    "energy_per_site": -0.7783541417738098
  },
  "no_record_reason": null
}