README.md

---
license: cc-by-4.0
tags:
  - materials-science
  - dft
  - charge-density
  - r2scan
  - bader
  - crystal-structure
---

# LeMat-Rho

**LeMat-Rho** is a dataset of ~69,000 inorganic crystal structures computed with the **r2SCAN meta-GGA functional** in VASP, featuring charge densities, Bader charges, forces, stresses, and energies. It is part of the [LeMaterial](https://huggingface.co/LeMaterial) ecosystem.

## Dataset Summary

| Property | Value |
|---|---|
| Materials | 69,117 |
| Functional | r2SCAN |
| Sources | AFLOW (agm), OQMD (oqmd-), Materials Project (mp-) |
| Bader charge coverage | 86.2% (59,613 materials) |
| Charge density grid | 15×15×15 (lossy compressed via pyrho) |
| DDEC6 charges | Planned for future release |

## Sources

| Source | Materials |
|---|---|
| AFLOW (`agm*`) | 38,925 |
| OQMD (`oqmd-*`) | 29,611 |
| Materials Project (`mp-*`) | 581 |

## Workflow

Each material was computed with a 4-step VASP pipeline:

1. **PreStaticMaker** — initial single-point on unrelaxed geometry
2. **RelaxMaker_1** — geometry relaxation (r2SCAN)
3. **RelaxMaker_2** — second relaxation pass (r2SCAN)
4. **StaticMaker** — final NSW=0 single-point; source of all reported properties

Forces, stresses, and energies are from the final static calculation. Charge densities (CHGCAR, AECCAR0, AECCAR1, AECCAR2) are from the StaticMaker output.

Bader charges were computed using the [Bader charge analysis code](http://theory.cm.utexas.edu/henkelman/code/bader/) (Henkelman group) with AECCAR0+AECCAR2 as the reference charge density.

## Columns

| Column | Type | Unit | Description |
|---|---|---|---|
| `immutable_id` | string | — | Unique material identifier (e.g. `agm001234567`) |
| `elements` | list[string] | — | Element symbols present |
| `nelements` | int | — | Number of distinct elements |
| `nsites` | int | — | Number of atoms in the unit cell |
| `chemical_formula_reduced` | string | — | Reduced formula (e.g. `Fe2O3`) |
| `chemical_formula_anonymous` | string | — | Anonymous formula (e.g. `A2B3`) |
| `chemical_formula_descriptive` | string | — | Full descriptive formula |
| `lattice_vectors` | list[list[float]] | Å | 3×3 lattice matrix |
| `cartesian_site_positions` | list[list[float]] | Å | Atomic positions |
| `species_at_sites` | list[string] | — | Element at each site |
| `functional` | string | — | DFT functional (`r2scan`) |
| `energy` | float | eV | Total DFT energy (final static) |
| `energy_corrected` | float | eV | Energy with MP2020 corrections (equals `energy` for r2SCAN) |
| `forces` | list[list[float]] | eV/Å | Per-atom forces from final static |
| `stress_tensor` | list[list[float]] | kBar | 3×3 stress tensor from final static |
| `bader_charges` | list[float] | e | Bader net charges per atom (positive = cationic); null if AECCAR files absent |
| `bader_atomic_volume` | list[float] | ų | Bader atomic volumes per atom |
| `ddec6_charges` | list[float] | e | DDEC6 net charges per atom (null in current release; planned) |
| `compressed_charge_density` | string | — | Lossy-compressed CHGCAR (15×15×15 grid, JSON-encoded via pyrho) |
| `compressed_aeccar0` | string | — | Lossy-compressed AECCAR0 (core charge density) |
| `compressed_aeccar1` | string | — | Lossy-compressed AECCAR1 |
| `compressed_aeccar2` | string | — | Lossy-compressed AECCAR2 (valence charge density) |
| `charge_density_grid_shape` | list[int] | — | Grid dimensions [nx, ny, nz] |
| `space_group_it_number` | int | — | International Tables space group number |
| `bawl_fingerprint` | string | — | Structure fingerprint (BAWL hasher) |
| `magnetic_moments` | list[float] | μ_B | Per-atom magnetic moments (null if not spin-polarized) |
| `total_magnetization` | float | μ_B | Total cell magnetization |
| `cross_compatibility` | bool | — | Cross-compatibility flag with other LeMaterial datasets |

## Usage

```python
from datasets import load_dataset

ds = load_dataset("LeMaterial/LeMat-Rho", split="train")

# Filter to materials with Bader charges
with_bader = ds.filter(lambda x: x["bader_charges"] is not None)
print(f"Materials with Bader charges: {len(with_bader)}")

# Access a material
row = ds[0]
print(row["chemical_formula_reduced"], row["bader_charges"])
```

## Notes

- **Charge density compression**: The stored charge densities are lossy-compressed to a 15×15×15 grid using [pyrho](https://github.com/materialsproject/pyrho). This is suitable for qualitative analysis and ML feature extraction but not for quantitative integration (e.g. re-running Bader). The raw CHGCAR files are available on request.
- **Bader coverage**: ~13.8% of materials lack Bader charges because their AECCAR files are absent from the source S3 data. This is consistent across all three source databases and reflects an upstream calculation issue.
- **DDEC6 charges**: `ddec6_charges` is null in this release. A follow-up patch run is planned.
- **r2SCAN functional**: All calculations use the r2SCAN meta-GGA functional. MP2020 energy corrections are PBE-specific and do not apply; `energy_corrected` equals `energy` for all rows.

## Citation

If you use this dataset, please cite the underlying databases:

- **AFLOW**: Curtarolo et al., *Computational Materials Science* 58, 218–226 (2012)
- **OQMD**: Saal et al., *JOM* 65, 1501–1509 (2013); Kirklin et al., *npj Computational Materials* 1, 15010 (2015)
- **Materials Project**: Jain et al., *APL Materials* 1, 011002 (2013)
- **Bader analysis**: Henkelman et al., *Computational Materials Science* 36, 354–360 (2006)
- **r2SCAN functional**: Furness et al., *J. Phys. Chem. Lett.* 11, 8208–8215 (2020)
- **pyrho**: Shen, J.-X. et al. (2022). Sci Data, 9(661), 1–7. doi: 10.1038/s41597-022-01746-z