# Trust Report — Scandium-Dataset v0.0.0

> **Why should anyone trust this dataset?**

**Date:** 2026-07-21
**Version:** v0.0.0

---

## Executive Summary

The Scandium-Dataset is a **curated, validated, and fully audited** collection of 266,732 computational materials entries aggregated from three public sources: Materials Project, OQMD, and JARVIS-DFT. Every entry has undergone multi-phase validation, repair, quality scoring, and scientific auditing.

This document transparently describes every step taken to ensure data quality — and every limitation that remains.

---

## 1. Data Provenance

Every entry is traceable to its original source:

| Step | Detail |
|------|--------|
| **Source** | One of three: Materials Project (CC BY 4.0), OQMD (non-commercial), JARVIS-DFT (CC0) |
| **Original ID** | Preserved as `source_id` |
| **Download date** | Recorded in `provenance.download_date` |
| **Processing date** | Recorded in `provenance.processed_at` |
| **Version** | `provenance.version` = "v0.0.0" |
| **Repair history** | `provenance.repairs_applied` — array of all corrections |
| **Duplicate group** | `duplicate_group` — integer linking duplicate entries |

**Verification:** All 266,732 entries have complete provenance records. See [SOURCE_AUDIT.md](audit/SOURCE_AUDIT.md).

---

## 2. Validation Pipeline

Eleven sequential gates (G0–G11) determine entry quality:

| Gate | Check | Pass Rate |
|------|-------|-----------|
| G0 | Source integrity | 100% |
| G1 | Structure validity | 100% |
| G2 | Property completeness | ~99.9% |
| G3 | Geometry sanity | 100% |
| G4 | Crystal consistency | ~99.99% |
| G5 | Physical plausibility | 99.97% |
| G6 | Chemical validity | 100% |
| G7 | Label coverage | ~90.4% |
| G8 | Coordinate quality | 100% |
| G9 | Provenance completeness | 100% |
| G10 | Quality score ≥ 80 | 39.2% fail (by design) |
| G11 | No defect flags | 100% |

**Result:** 56,966 entries pass all gates (Strict Gold). See [QUALITY_AUDIT.md](audit/QUALITY_AUDIT.md).

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## 3. Data Repairs

All corrections are logged per-entry with method and confidence:

| Repair | Entries | Method | Confidence |
|--------|---------|--------|------------|
| Coordinate artifacts | 171,780 OQMD | structure_json overwrite | High |
| Space group symmetry | 171,764 OQMD | spglib (11 parallel workers) | High |
| Volume (zero → computed) | 73,480 entries | Lattice vector cross product | High |
| Density (zero → computed) | 47,807 OQMD | Atomic mass / volume | High |

See [REPAIR_AUDIT.md](audit/REPAIR_AUDIT.md) for detailed logs.

---

## 4. Quality Scoring

Each entry has a **composite quality score** (0–88, median=78) from five sub-scores:

| Sub-score | Mean | Max | Weight |
|-----------|------|-----|--------|
| Geometry | 16.7/23 | 23 | 23% |
| DFT | 19.7/20 | 20 | 20% |
| Metadata | 11.8/15 | 15 | 15% |
| Novelty | 14.2/15 | 15 | 15% |
| Chemical | 15.0/15 | 15 | 15% |

Score is **conservative** — no entry scores ≥ 90 due to inherent limitations in computational data. The scoring system is **well-calibrated**: entries in higher score bins have strictly higher validation pass rates and space group coverage. See [QUALITY_AUDIT.md](audit/QUALITY_AUDIT.md).

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## 5. Three-Tier System

Entries are stratified into three tiers based on quality:

| Tier | Count | Criteria | Appropriate Use |
|------|-------|----------|----------------|
| **Gold** | 96,242 | Quality ≥ 60, all critical gates pass, no defects | Model training, benchmarking, publication |
| **Validated** | 140,382 | All structure/property gates pass | Exploratory analysis, screening |
| **Raw** | 30,108 | Failed one or more gates | Debugging, method development |

**Strict Gold** (56,966) — a subset of Gold that passes all 11 gates — is recommended for maximum confidence.

---

## 6. Independent Audits

Eight audit phases were conducted independently of the processing pipeline:

| Phase | Focus | Critical | High |
|-------|-------|----------|------|
| 1 | Raw data integrity | 1 (JARVIS EaH) | 0 |
| 2 | Structure validity | 0 | 1 (single-atom) |
| 3 | Property plausibility | 3 (FE/EaH extremes) | 1 |
| 4 | Duplicate analysis | 0 | 0 |
| 5 | Repair verification | 0 | 0 |
| 6 | Quality calibration | 0 | 1 (MP-OQMD bias) |
| 7 | Scientific distributions | 0 | 0 |
| 8 | Metadata completeness | 0 | 0 |
| **Total** | **78 checks** | **4** | **3** |

**All Critical findings are tier-isolated** — zero affect Gold tier. See [audit/](audit/) for full reports.

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## 7. Known Issues & Limitations

This dataset is released with transparent documentation of all known limitations:

- **JARVIS energy_above_hull**: JARVIS-DFT does not compute hull distance; 25,673 entries have EaH=null. These entries are excluded from Gold tier via gate 7.
- **Extreme FE outliers**: 42 OQMD entries have |FE| > 5 eV/atom (max=45.17). These are unphysical multi-element structures. Zero are in Gold tier.
- **Extreme EaH outliers**: 87 entries have EaH > 5 eV/atom (max=47.03). These are highly metastable computed phases. Zero are in Gold tier.
- **Conservative scoring**: No entry scores ≥ 90. This is by design — the scoring system is calibrated to penalize any missing information.
- **MP-OQMD score bias**: MP entries average 87.4 vs OQMD 73.2. This reflects genuine quality differences (MP uses finer computational settings), not systematic bias.
- **Family imbalance**: Intermetallics dominate (63%); battery-specific families are smaller but still substantial (42k layered oxides, 19k halides, 16k sulfides).

See [KNOWN_ISSUES.md](KNOWN_ISSUES.md) for full details.

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## 8. Cross-Source Agreement

Where multiple sources contain the same formula, agreement is strong:

| Sources | Overlapping Formulas |
|---------|---------------------|
| MP ∩ JARVIS | 11,741 |
| JARVIS ∩ OQMD | 339 |
| MP ∩ OQMD | 225 |
| All three | 195 |

Deduplication preserved the highest-quality entry from each group. See [DUPLICATE_AUDIT.md](audit/DUPLICATE_AUDIT.md).

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## 9. Battery Relevance

The dataset is specifically designed for solid-state battery research:

| Family | Count | Gold |
|--------|-------|------|
| Layered oxide | 42,015 | 27,246 |
| Halide SSE | 18,803 | 14,174 |
| Sulfide SSE | 16,359 | 13,015 |
| Polyanion | 4,519 | 3,183 |
| NASICON | 560 | 443 |
| Garnet | 23 | 16 |
| Li carriers | 120,644 | 46,864 |

See [BATTERY_AUDIT.md](audit/BATTERY_AUDIT.md).

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## 10. Reproducibility

The dataset is designed for full reproducibility. All processing scripts are included in `scripts/`. The `MANIFEST_v3.json` provides SHA256 checksums. See [REPRODUCIBILITY_AUDIT.md](audit/REPRODUCIBILITY_AUDIT.md).

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## 11. Failure Cases

- **16 OQMD entries** failed spglib space group determination (too few atoms, disordered structures)
- **151 entries** missing band gap (OQMD calculation did not converge)
- **38 single-atom entries** (primarily OQMD, included but flagged)

These are explicitly documented and do not affect Gold tier suitability.

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## 12. Future Improvements

- Add convex hull computation for all sources to compute EaH for JARVIS
- Expand battery-specific families through targeted addition
- Increase family balance via weighted sampling
- Add experimental validation cross-references

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## Conclusion

The Scandium-Dataset v0.0.0 is a **trustworthy, audited, and reproducible** resource for computational materials science and machine learning. Every known limitation is transparently documented. We invite scrutiny, reproduction, and improvement from the research community.