---
license: cc-by-4.0
pretty_name: TRIP50 Reaction-Energy Benchmark
size_categories:
  - n<1K
task_categories:
  - tabular-regression
tags:
  - chemistry
  - mlip
  - benchmark
  - dft
  - coupled-cluster
  - reaction-energy
  - transition-state
  - radical
  - triplet
  - ase
language:
  - en
configs:
  - config_name: species
    data_files: data/species.parquet
  - config_name: reactions
    data_files: data/reactions.parquet
  - config_name: aliases
    data_files: data/aliases.parquet
---

# TRIP50

TRIP50 is a 50-reaction benchmark for radical and triplet thermochemistry and forward/reverse barriers, with a DLPNO-CCSD(T) reference and 46 DFT method totals computed on the same geometries. The benchmark is small, well-curated, and chemically diverse — designed to evaluate methods on **relative** energetics: reaction energies (ΔE_rxn), forward barriers (ΔE‡_fwd), and reverse barriers (ΔE‡_rev).

This release packages the structures and reference energies as a single Hugging Face dataset for use evaluating **machine-learning interatomic potentials (MLIPs)** alongside conventional DFT.

> **No forces.** TRIP50 is a single-point energy benchmark on relaxed stationary points. MLIPs that require force training data should look elsewhere; MLIPs being evaluated on relative energetics work directly.

## Contents

| File | Rows | Notes |
|---|---|---|
| `data/trip50.extxyz`  | 156 frames | ASE-readable, all 47 method energies on the comment line |
| `data/species.parquet` | 156 | one row per canonical structure, full float64 precision |
| `data/reactions.parquet` | 50 | reaction definitions with reference Δs in **kcal/mol** |
| `data/aliases.parquet` / `aliases.csv` | 30 | logical alias map (no duplicate xyz files shipped) |
| `data/methods.json` | – | slug ↔ display-name mapping for the 47 method columns |
| `data/MANIFEST.sha256` | – | digest of every payload file |

## Schemas

### `species.parquet`

| column | type | notes |
|---|---|---|
| `species_id` | string | canonical name, e.g. `1-R1`, `26-TS` |
| `rxn_id` | int32 | 1..50 |
| `role` | string | `R1` / `R2` / `TS` / `P1` / `P2` |
| `n_atoms` | int32 | |
| `atomic_numbers` | list&lt;int8&gt; | length `n_atoms` |
| `positions` | list&lt;list&lt;float64, 3&gt;&gt; | Cartesian, **Å** |
| `charge` | int8 | always `0` |
| `multiplicity` | string | `singlet` / `doublet` / `triplet` |
| `spin_multiplicity` | int8 | `1` / `2` / `3` |
| `energy_dlpno_ccsd_t` | float64 | reference, **Hartree** |
| `energy_<slug>` × 46 | float64 | DFT methods, Hartree (slugs in `methods.json`) |

### `reactions.parquet`

| column | type | notes |
|---|---|---|
| `rxn_id` | int32 | 1..50 |
| `category` | string | one of `C-C`, `C-O`, `C-S`, `HAT`, `Si-X`, `C-Hal`, `N-X` (Figure 2 of the source paper) |
| `r1_species_id`, `r2_species_id`, `ts_species_id`, `p1_species_id`, `p2_species_id` | string (nullable) | post-alias canonical IDs; `null` = unimolecular leg (contributes 0 H) |
| `is_unimolecular_reactant`, `is_unimolecular_product` | bool | |
| `dE_rxn_kcal_dlpno` | float64 | E(P1)+E(P2) − E(R1)−E(R2), **kcal/mol** |
| `dE_fwd_kcal_dlpno` | float64 | E(TS) − E(R1)−E(R2), kcal/mol |
| `dE_rev_kcal_dlpno` | float64 | E(TS) − E(P1)−E(P2), kcal/mol |

### `aliases.parquet`

| column | type | notes |
|---|---|---|
| `alias` | string | non-canonical species id seen in the rxn definitions |
| `canonical` | string | the species_id actually present in `species.parquet` |

Aliases are **logical only** — the dataset ships one xyz per canonical structure. A consumer evaluating reaction `50` should look up `p1_species_id = "48-R1"` (which is the same molecule as `50-P1`).

## Conventions

- **Units**. Total energies in `species.parquet` and `trip50.extxyz` are in **Hartree**. Reference reaction-level Δ values in `reactions.parquet` are in **kcal/mol** (1 Hartree = 627.5094740631 kcal/mol).
- **Charge & spin**. Every species is neutral. Multiplicities span singlet / doublet / triplet. Spin-unaware MLIPs will incur unavoidable error on the radical and triplet species — a known limitation of the dataset for such models.
- **Unimolecular legs**. Reactions with a single reactant or product have the corresponding `R2` / `P2` field set to `null` in `reactions.parquet`, and the missing partner contributes 0 H to ΔE sums. This convention is inherited from the source paper.
- **Alias resolution**. Always go through `reactions.parquet` (which already stores post-alias canonical IDs). Never assume `{rxn}-{role}.xyz` exists for every (rxn, role).
- **Precision**. The Parquet artefacts are full float64. The `trip50.extxyz` representation rounds positions to ASE's default 8-decimal format (≈ 5 × 10⁻⁹ Å — far below physical precision). Use `species.parquet` if exact byte-identity matters.

## Usage

### Hugging Face `datasets`

```python
from datasets import load_dataset

species = load_dataset("patonlab/trip50", "species", split="train")
reactions = load_dataset("patonlab/trip50", "reactions", split="train")

print(species[0]["species_id"], species[0]["energy_dlpno_ccsd_t"], "Hartree")
print(reactions[0]["dE_fwd_kcal_dlpno"], "kcal/mol")
```

### ASE

```python
from ase.io import read

frames = read("hf://datasets/patonlab/trip50/data/trip50.extxyz", index=":")
e_dlpno = frames[0].info["energy_dlpno_ccsd_t"]   # Hartree
mult = frames[0].info["multiplicity"]              # 'singlet' | 'doublet' | 'triplet'
```

A reference MLIP evaluator that prints a per-method MAE table is in [`examples/evaluate_mlip.py`](examples/evaluate_mlip.py).

## Limitations

- **No forces or gradients.** Relative reaction energetics only.
- **Single geometries.** No conformer ensembles; no thermochemical corrections (ΔH / ΔG); no solvent corrections.
- **Reference is DLPNO-CCSD(T)**, not experiment. Methods that systematically agree with the reference may still disagree with experiment.
- **Spin-aware models recommended.** Roughly half the species are open-shell.

## Citation

Please cite the original TRIP50 publication when using this dataset. See `CITATION.cff` for a machine-readable record.

```bibtex
@article{trip50,
  title   = {Fundamental Study of Density Functional Theory Applied to Triplet State
             Reactivity: Introduction of the {TRIP50} Data Set},
  author  = {Hughes, William B. and Popescu, Mihai V. and Paton, Robert S.},
  journal = {Journal of Chemical Theory and Computation},
  volume  = {22},
  pages   = {3530--3542},
  year    = {2026},
  doi     = {10.1021/acs.jctc.6c00144}
}
```

## License

[Creative Commons Attribution 4.0 International (CC-BY-4.0)](LICENSE).