Scandium-Dataset Paper Outline
Target Venues (in priority order):
- NeurIPS Datasets & Benchmarks (if benchmark experiments are the core contribution)
- Scientific Data (if curation methodology is the core contribution)
- npj Computational Materials (if materials science insight is the core contribution)
- J. Chem. Inf. Model. (domain-specific data resource)
Title
Scandium: A Curated Multi-Source Dataset with Quality Tiering for ML-Driven Solid-State Battery Discovery
Authors
Scandium Labs (individual names if available)
Abstract (draft)
We introduce Scandium-Dataset, a unified computational materials dataset of 266,732 DFT-computed entries aggregated from Materials Project, OQMD, and JARVIS-DFT. Unlike prior harmonization efforts, Scandium implements a calibrated 4-tier quality system (Strict Gold / Gold / Validated / Raw) with per-entry provenance tracking, 31,997 duplicates removed, and 137,405 repaired structures. We provide frozen benchmark splits across four held-out strategies (random, composition, family, chemistry), enabling reproducible evaluation of generalization to unseen compositions and material families. Baseline experiments with a composition-only model show that training on Gold-tier data (96,242 entries) consistently outperforms training on the full dataset, achieving FE MAE of 0.298 vs 0.392 on random splits and 1.384 vs 1.657 on chemistry held-out splits — validating the tiering strategy. Battery (82,925 entries) and electrolyte (41,665 entries) subsets are provided for domain-specific applications. The dataset is released with full documentation, audit reports, and known limitations. All code and data are publicly available.
1. Introduction
Problem Statement
- Solid-state battery discovery is bottlenecked by slow DFT screening
- ML acceleration requires high-quality, well-characterized training data
- Existing data is scattered (MP, OQMD, JARVIS differ in schema, quality, conventions)
Gaps in Prior Work
- Prior harmonization (LeMat-Traj) unifies schema but doesn't tier by quality
- Existing benchmarks (Matbench) use single-source data and lack OOD splits
- Battery-specific datasets (Electrolyte Genome) are small and experimental-only
Contributions (numbered)
- Multi-source unification with 4-tier quality system and 11 validation gates
- Cross-source agreement quantification and systematic bias documentation
- Battery/electrolyte classification methodology with 10 material families
- Frozen benchmark splits (4 types) with OOD held-out configurations
- Baseline experiments validating the tiering system
2. Related Work
(Expand from related_work.md)
- Materials databases: MP, OQMD, JARVIS, AFLOW, NOMAD
- Harmonized datasets: LeMat-Traj (closest prior art — explicit comparison table)
- Benchmarks: Matbench, JARVIS-Leaderboard
- Battery-specific: Electrolyte Genome, BatteryHub
- Novelty positioning: Tiering methodology + battery curation + OOD splits
3. Curation Methodology
3.1 Source Selection
- Why MP, OQMD, JARVIS? Coverage, complementarity, license variation
- Extraction dates, API versions pinned for reproducibility
3.2 Schema Unification
- Field mapping across sources
- Unit normalization
- Structure standardization (pymatgen JSON)
3.3 Deduplication
- 31,997 duplicates removed across 21,140 groups
- Structure matching method (pymatgen StructureMatcher)
- Priority rules for choosing which entry to keep
3.4 Repair Pipeline
- OQMD coordinate artifacts (137,405 entries):
coords_are_cartesian=False - OQMD space group determination (171,764 entries): spglib symmetry pass
- Volume/density repair (73,480 entries): extraction from structure_json
- JARVIS volume extraction (25,673 entries)
3.5 Quality Scoring
- 5 sub-scores (geometry, DFT, metadata, novelty, chemical)
- Composite score range: 48–88 (intentionally conservative)
- Calibration: score 80-90 predicts 85.2% validation rate, 0.18 eV FE MAE
3.6 Tiering System
- 4 tiers with cumulative gates:
- Strict Gold (56,966): 11 gates, quality ≥ 80, full provenance, no defects
- Gold (96,242): 8 gates, validated + unique + stable + complete metadata
- Validated (140,382): 5 gates, valid structure + targets + no critical issues
- Raw (30,108): source + formula present
- Gate definitions and pass/fail criteria for each tier
3.7 Provenance Tracking
- Per-entry checksum, repair history, tier gate results, dedup resolution
- Enables auditability and reproducibility
3.8 Material Family Classification
- 10 families based on element composition
- Family distribution and battery relevance assessment
- Known issue: garnet undercount (23 entries)
4. Dataset Analysis
4.1 Overall Statistics
(Table: entries per source, per tier, per family)
4.2 Property Distributions
(Figures: FE, EaH, BG histograms by source and tier)
4.3 Cross-Source Agreement
- 11,741 formulas overlapping between MP and JARVIS
- FE MAE across overlaps: 0.20 eV/atom
- Source-level biases documented (MP mean quality 87.4 vs OQMD 73.2)
4.4 Quality Score Calibration
- Monotonic relationship between score and downstream prediction error
- Figure: score bin → validation rate, FE MAE, EaH MAE
4.5 Tier Impact Analysis
- Outlier removal effectiveness (Gold excludes 42 extreme-FE OQMD entries)
- Defect distribution by tier
- Missing data analysis (EaH for JARVIS: 100% missing by source limitation)
4.6 Battery and Electrolyte Subset Statistics
(Per-family breakdown, tier distribution within subsets)
5. Benchmark Baselines
5.1 Experimental Setup
- 4 split types (random, composition-held-out, family-held-out, chemistry-held-out)
- 2 training configurations (full dataset vs Gold-tier only)
- 8 experiments total
5.2 Model
- Composition-only: bag-of-elements + RF + Ridge ensemble
- Rationale: fast, reproducible, structure-agnostic lower bound
5.3 Results
Key table (8 rows):
| Training Data | Split | FE MAE | EaH MAE | BG MAE |
|---|---|---|---|---|
| Full | random | 0.392 | 0.224 | 0.494 |
| Gold | random | 0.298 | 0.024 | 0.762 |
| Full | composition | 0.390 | 0.223 | 0.497 |
| Gold | composition | 0.306 | 0.024 | 0.772 |
| Full | family | 0.739 | 0.169 | 1.105 |
| Gold | family | 0.458 | 0.019 | 0.943 |
| Full | chemistry | 1.657 | 0.355 | 1.966 |
| Gold | chemistry | 1.384 | 0.027 | 2.129 |
5.4 Analysis
- Gold-tier training consistently beats full-dataset on FE and EaH despite 3× less data
- EaH dramatically benefits from Gold filtering (excludes JARVIS with no EaH, filters OQMD outliers)
- Chemistry held-out is hardest — negative R² for both configurations
- Band gap trade-off — Gold has fewer metals (BG=0), making BG prediction harder
- Per-family analysis reveals model weaknesses (intermetallic bias, garnet data scarcity)
5.5 Discussion
- The tiering system is empirically validated: cleaner data beats more data
- OOD splits reveal limits of composition-only models
- Roadmap for structure-aware models (CGCNN, MEGNet, ALIGNN)
6. Limitations
(Lift directly from KNOWN_ISSUES.md)
- JARVIS EaH missing (25,673 entries) — fundamental source limitation
- MP vs OQMD quality score gap (87.4 vs 73.2 mean)
- Family imbalance (~63% intermetallics)
- Garnet family undercount (23 entries)
- No experimental validation — purely computational
- License complexity — 3 different licenses across sources
- Conservative quality scoring (max score: 88)
- No Docker container (since resolved in v0.1.0-rc.1)
- No DOI assigned yet (Zenodo archival in progress)
7. Conclusion
- Summary of contributions
- Empirical validation of tiering system via benchmark experiments
- Roadmap: JARVIS EaH computation, NOMAD/AFLOW integration, experimental data, ionic conductivity computation
- Call for community adoption
Figures Needed
- Property distributions — FE, EaH, BG histograms colored by source (3 panels)
- Quality score calibration — score bin → validation rate (line plot with confidence bands)
- Cross-source agreement — MP vs JARVIS FE scatter plot (11,741 overlapping formulas)
- Tier impact — FE MAE bar chart across tiers (4 bars)
- Benchmark results — FE MAE across 4 splits, full vs Gold (grouped bar chart)
- Family distribution — bar chart of 10 families with battery relevance labels
- Battery subset composition — pie chart or treemap
Tables Needed
- Source comparison (MP, OQMD, JARVIS — size, properties, license)
- Tier system (4 tiers, counts, gate criteria)
- Family classification (10 families, criteria, battery relevance)
- Benchmark results (8 rows as above)
- Comparison with prior work (Scandium vs LeMat-Traj, Matbench, JARVIS)
- Dataset statistics per source (mean FE, EaH, BG, quality score)
- Cross-source overlap statistics (11,741 formulas, FE MAE by source pair)
Submission Checklist
- DOI obtained from Zenodo
- License conflict resolved (LICENSE_BREAKDOWN.md added)
- per-entry
licensefield added to dataset - Baseline benchmark results computed (8 experiments)
- Related work analyzed against LeMat-Traj, Matbench, JARVIS
- Battery/electrolyte methodology documented
- Version bumped to v0.1.0
- Evaluation runner fixed (metrics module created)
- Code and data archived for reproducibility
- All known issues documented