Science

Foundation models

MACE ships pre-trained potentials for distinct chemical domains. Choosing the right one — and understanding its level of theory — is the single most important decision for a meaningful result.

MACE-MP-0

  • Scope: materials, crystals, surfaces, and bulk systems — 89 elements across the periodic table.
  • Training data: Materials Project DFT calculations (PBE+U functional).
  • Accuracy: PBE-level. Expect roughly 0.1–0.5 eV/atom overbinding relative to experiment.
  • D3 dispersion: supported and recommended for van der Waals systems (layered materials, molecular crystals).
  • Energy reference: isolated-atom energies. Typical range −1 to −15 eV/atom.

MACE-OFF

  • Scope: organic molecules and drug-like compounds.
  • Supported elements: H, C, N, O, F, P, S, Cl, Br, I (10 elements).
  • Training data: ωB97M-D3BJ reference data (near coupled-cluster quality for organic chemistry).
  • Energy reference: a different convention from MACE-MP-0. Typical range −100 to −600 eV/atom.

Do not enable D3 with MACE-OFF

MACE-OFF is trained on ωB97M-D3BJ data — dispersion is already included. Enabling the D3 correction double-counts dispersion interactions. SimpleAtom disables the D3 toggle automatically when MACE-OFF is selected.

Model sizes

Each foundation model is available in three sizes:

SizeSpeedAccuracyUse case
smallFastestLeast accurateQuick screening, large systems
mediumBalancedGoodGeneral use (default)
largeSlowestBestProduction results, publication

Custom models

You can upload your own .model checkpoint trained with mace-torch (for example, a model fine-tuned with mace_run_train). SimpleAtom loads it with MACECalculator, runs the calculation identically to the foundation models, and can compare your model against a foundation model with agreement metrics (MAE, RMSE, R²).

Choosing a model

Is your system purely organic (only H, C, N, O, F, P, S, Cl, Br, I)?
  ├─ Yes → MACE-OFF
  └─ No  → MACE-MP-0

Do you need van der Waals / dispersion corrections?
  ├─ MACE-MP-0 → enable D3 dispersion
  └─ MACE-OFF  → do nothing (already included)

Reference conventions differ

MACE-MP-0 and MACE-OFF use different energy-reference conventions, so their absolute energies differ by an order of magnitude. Never compare absolute energies across the two models — see Units & conventions.