docs/validation.md

Validation

Validation Pipeline

Every entry in the Scandium Dataset passes through a deterministic validation pipeline before entering its tier.

Structural Validation

1. Nsites ≥ 2: Eliminates single-atom entries (no meaningful structure)
2. Volume > 10 ų: Eliminates entries with zero or implausible volume
3. Min distance check: Flags overlapping atoms (OQMD artifact detector)
4. Space group computation: spglib symmetry detection

Property Validation

1. Target presence: At least 2 of 3 targets (FE, EaH, BG) must exist
2. Physical range: FE in [-5, +5] eV/atom, BG in [0, ~10] eV
3. Stability check: EaH < 0.1 eV/atom or null (for Gold tier)

Quality Flags

Flags are generated by validators and ingested during scoring:

Flag	Meaning
overlapping_atoms	Min distance < 0.5 Å
corrupted_structure	Structure JSON unparseable
extreme_*	Property outside physical range
heavy_element	Contains elements with Z > 92
noble_gas	Contains noble gas elements
missing_spacegroup	No space group computed
bad_volume	Volume missing or zero
missing_EaH	EaH not available (known for JARVIS)

Tier Gates

Raw (Gate 0)

• Source and formula present
• Fallthrough for all entries

Validated (Gates 1-4)

1. Valid structure (nsites ≥ 2, volume > 10)
2. At least 2 of 3 targets present
3. No critical quality flags
4. Quality score ≥ 70

Gold (Gates 5-8)

5. Not a duplicate (no duplicate_group)
6. No label conflicts (no disagreement flags)
7. Stable or near-stable (EaH < 0.1 or null)
8. Complete metadata (space_group, density, elements)

Strict Gold (Gates 9-11)

9. Provenance complete (source_id + checksum)
10. Quality score ≥ 80 (calibrated: 85.2% valid at this threshold)
11. No known defects (volume > 0, density > 0, space_group present)

Verification Reports

See reports/validation_reports/ for:

• Per-source validation results
• Per-family validation results
• Cross-source agreement verification