# Third-party model weights

## `orb-v3-direct-20-omat-20250404.ckpt`

ORB-v3 machine-learned interatomic potential, used by this project **only to build the
ORB atom-embedding caches**. It is redistributed here unmodified, as a convenience, because
the cache-building step cannot run without it.

| | |
|---|---|
| Upstream | [orbital-materials/orb-models](https://github.com/orbital-materials/orb-models) |
| Official download | `https://orbitalmaterials-public-models.s3.us-west-1.amazonaws.com/forcefields/orb-v3/orb-v3-direct-20-omat-20250404.ckpt` |
| Size | 98 MiB |
| `sha256` | `5b8dcf334f0bd47a9a84b62f07cee1f819e2293cb665fe423213b23b5f9c3c49` |
| License | Apache License 2.0 — see `LICENSE-orb-models.txt` |
| Modified? | **No.** Byte-identical to the official release. |

Copyright belongs to Orbital Materials. This redistribution is made under the terms of the
Apache License 2.0; the license text is included alongside this file.

### Verify after download

```bash
sha256sum orb-v3-direct-20-omat-20250404.ckpt
# expected: 5b8dcf334f0bd47a9a84b62f07cee1f819e2293cb665fe423213b23b5f9c3c49
```

### Where it goes

Place it at `$PROJECT_ROOT/models/orb-v3-direct-20-omat-20250404.ckpt`.

### What actually reads it

- **Stage-2 property training does NOT read this checkpoint.** It only reads the prebuilt
  ORB caches given by `--cache-prefix`. If a run asks for this file, it means it is
  *building* caches rather than consuming them.
- The evaluation path pins this exact hash as `cache_encoder_weights_sha256` in
  `3D_Property/step_6500/checkpoint_metadata.json` and compares against it, so a mismatched
  or re-downloaded-but-different checkpoint will fail the check.