{
  "counts": {
    "above_hull": 11,
    "entries": 89,
    "intervals": 4,
    "vertices": 5
  },
  "elements": [
    "H",
    "NB"
  ],
  "flags": [
    "degenerate_endpoints",
    "has_intermediate_compounds",
    "mp_agreement_not_comparable",
    "theoretical_vertices"
  ],
  "isotherms": [
    {
      "intervals": [
        {
          "intercept": 0.0,
          "kind": "two_phase",
          "left": {
            "phase": "oqmd-5539",
            "x": 0.0
          },
          "mu_a_rel": 0.0,
          "mu_b_rel": -0.68504005436835,
          "right": {
            "phase": "oqmd-10076",
            "x": 0.3333333333333333
          },
          "slope": -0.68504005436835,
          "x_hi": 0.3333333333333333,
          "x_lo": 0.0
        },
        {
          "intercept": -0.24679431718417297,
          "kind": "two_phase",
          "left": {
            "phase": "oqmd-10076",
            "x": 0.3333333333333333
          },
          "mu_a_rel": -0.24679431718417297,
          "mu_b_rel": -0.19145142000000406,
          "right": {
            "phase": "oqmd-1481828",
            "x": 0.5
          },
          "slope": 0.0553428971841689,
          "x_hi": 0.5,
          "x_lo": 0.3333333333333333
        },
        {
          "intercept": -0.40619071218418246,
          "kind": "two_phase",
          "left": {
            "phase": "oqmd-1481828",
            "x": 0.5
          },
          "mu_a_rel": -0.40619071218418246,
          "mu_b_rel": -0.03205502499999463,
          "right": {
            "phase": "oqmd-1979251",
            "x": 0.6
          },
          "slope": 0.3741356871841878,
          "x_hi": 0.6,
          "x_lo": 0.5
        },
        {
          "intercept": -0.4542732496841743,
          "kind": "two_phase",
          "left": {
            "phase": "oqmd-1979251",
            "x": 0.6
          },
          "mu_a_rel": -0.4542732496841743,
          "mu_b_rel": 0.0,
          "right": {
            "phase": "oqmd-ref-Nb",
            "x": 1.0
          },
          "slope": 0.4542732496841743,
          "x_hi": 1.0,
          "x_lo": 0.6
        }
      ],
      "temperature_K": 0.0,
      "vertices": [
        {
          "collinear": false,
          "degenerate": [
            {
              "energy": 0.0,
              "phase": "oqmd-675624"
            }
          ],
          "energy": 0.0,
          "energy_per_atom": -3.32721224,
          "entries_at_x": 27,
          "formula": "H1",
          "nsites": 2,
          "phase": "oqmd-5539",
          "phase_kind": "structure",
          "spacegroup_number": 139,
          "spacegroup_symbol": "I4/mmm",
          "theoretical": false,
          "x": 0.0
        },
        {
          "collinear": false,
          "degenerate": [],
          "energy": -0.22834668478945,
          "energy_per_atom": -5.84673993666667,
          "entries_at_x": 5,
          "formula": "H2 Nb1",
          "nsites": 3,
          "phase": "oqmd-10076",
          "phase_kind": "structure",
          "spacegroup_number": 225,
          "spacegroup_symbol": "Fm-3m",
          "theoretical": false,
          "x": 0.3333333333333333
        },
        {
          "collinear": false,
          "degenerate": [],
          "energy": -0.21912286859208852,
          "energy_per_atom": -6.9563958225,
          "entries_at_x": 4,
          "formula": "H1 Nb1",
          "nsites": 4,
          "phase": "oqmd-1481828",
          "phase_kind": "structure",
          "spacegroup_number": 66,
          "spacegroup_symbol": "Cccm",
          "theoretical": true,
          "x": 0.5
        },
        {
          "collinear": false,
          "degenerate": [],
          "energy": -0.18170929987366974,
          "energy_per_atom": -7.590310075,
          "entries_at_x": 1,
          "formula": "H2 Nb3",
          "nsites": 10,
          "phase": "oqmd-1979251",
          "phase_kind": "structure",
          "spacegroup_number": 15,
          "spacegroup_symbol": "C2/c",
          "theoretical": true,
          "x": 0.6
        },
        {
          "collinear": false,
          "degenerate": [
            {
              "energy": 0.0,
              "phase": "oqmd-1215170"
            },
            {
              "energy": 0.0,
              "phase": "oqmd-1521870"
            },
            {
              "energy": 0.0,
              "phase": "oqmd-1521875"
            }
          ],
          "energy": 0.0,
          "energy_per_atom": -10.094018329999999,
          "entries_at_x": 25,
          "formula": "Nb",
          "nsites": null,
          "phase": "oqmd-ref-Nb",
          "phase_kind": "structure",
          "spacegroup_number": null,
          "spacegroup_symbol": "",
          "theoretical": false,
          "x": 1.0
        }
      ]
    }
  ],
  "mp_agreement": {
    "comparable": false,
    "comparable_note": "is_stable is derived by the extraction, not an upstream flag, so comparing it against a hull recomputed from the same energies tests the derivation rather than the data",
    "max_abs_delta_energy_above_hull": 6.524190909740213e-10,
    "only_mp_stable": [
      "oqmd-685533",
      "oqmd-ref-H"
    ],
    "only_ours_stable": [],
    "stable_sets_match": false
  },
  "provenance": {
    "above_hull_window_eV": 0.05,
    "builder_version": 1,
    "collinear_tol": 1e-12,
    "correction_model": "OQMD fit-partial ('standard' fit, applied upstream by OQMD; none added)",
    "degenerate_tol": 1e-06,
    "entry_pool": "all_nondeprecated",
    "is_stable_source": "derived",
    "observed_at": "2026-09-05T17:02:03Z",
    "snapshot_scope_elements": [],
    "snapshot_scope_kind": "full",
    "snapshot_sha256": "2a9393262c52ec35600424236c352a4cdb3291c8b25c1c6588f5e62abe8e0d8d",
    "source_release": "qmdb_v1_8_022026",
    "stability_tol": 0.0001,
    "thermo_type": "standard",
    "upstream_energy_corrections": "OQMD 'standard' fit (fit-partial of Kirklin et al. 2015): elemental reference energies of a subset of elements fitted to experimental formation enthalpies, applied by OQMD"
  },
  "reference": {
    "kind": "dft_fitted_elemental_reference_0K",
    "per": "atom",
    "temperature_K": 0.0,
    "units": "eV/atom"
  },
  "schema_version": 1,
  "system_id": "H-NB",
  "x_element": "NB"
}
