ML Foundation Potentials

Foundation Potentials Selection

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[!NOTE] Steps written server.tool are MCP tool calls: base.search_model_registry is the search_model_registry tool of the base server (mcp__base__search_model_registry, or mcp__plugin_atomistic-skills_base__search_model_registry when installed as a plugin). Without a connected server, run the same tools from the shell. Tools named in one command share a process, so a model loaded by load_model stays loaded:

${CLAUDE_SKILL_DIR}/../../venv/run cpu python -m src.mcp_server.cli base search_model_registry key=value

Goal

Select the appropriate machine learning interatomic potential (MLIP) for a given atomistic simulation task, balancing accuracy, computational cost, and material composition.

Model Selection Guide

[!NOTE] This list is not exhaustive. For a full list of available pre-trained checkpoints, refer to the load_model function documentation for each respective MCP server.

MatGL Models

Environment: mlip (MatGL >= 4, PyTorch Geometric)

• CHGNet-PES-MatPES-PBE-1M-2026.9 (the default CHGNet):
  • Use for PBE-level inorganic materials simulation.
  • Recommended when charge information and magnetic moments are involved (e.g., calculating transition metal valence states).
• CHGNet-PES-MatPES-r2SCAN-1M-2026.9:
  • Use for r2SCAN-level inorganic materials simulation, with the same strengths.
• TensorNet-PES-MatPES-r2SCAN-2025.2 / TensorNet-PES-MatPES-PBE-2025.2:
  • Use for r2SCAN- or PBE-level inorganic materials simulation.
  • Smaller and faster than CHGNet, suitable for dynamic simulations (MD, NEB, phonons).

FAIRCHEM Models

Environment: fairchem

• uma-s-1p1 (UMA checkpoints are gated on Hugging Face: request access at https://huggingface.co/facebook/UMA and set HF_TOKEN):
  • Use for organic and inorganic simulations.
  • Note: UMA models are typically slower and more expensive. Avoid for dynamic simulations with systems >500 atoms.
• uma-m-1p1:
  • Use for organic and inorganic simulations with <100 atoms.
• esen-md-direct-all-omol:
  • Use for organic ionic relaxation (ground state calculations).

MACE Models

Environment: mlip

• MACE-MH-1:
  • Latest multi-head foundation model. Use as default for most tasks.
  • omat_pbe head (default): General materials, balanced performance.
  • matpes_r2scan head: High-accuracy materials simulation.
  • omol head: Molecular systems, organic chemistry, organometallics.
  • spice_wB97M head: Molecular systems and organic chemistry.
  • oc20_usemppbe head: Surface catalysis, adsorbates.
• MACE-MATPES-r2SCAN-0:
  • Specialized for r2SCAN-level inorganic systems.
• MACE-OMAT-0-small:
  • Small, efficient model for materials.

Selection Criteria

Prioritize criteria in the following order:

0. Check the Local Model Registry (Always First)

Before selecting any foundation model, call search_model_registry to check whether a fine-tuned checkpoint already exists for the target chemical system:

base.search_model_registry(
    chemical_system="Li-Fe-P-O",   # elements of interest
    max_energy_mae=5.0,            # optional accuracy filter (meV/atom)
)

• If a match is found and checkpoint_exists = True, use that model directly — no foundation model selection or fine-tuning is needed.
• If a match is found but checkpoint_exists = False (file missing), fall through to the criteria below and plan a new fine-tuning run.
• If no match is found, continue with the criteria below to select the best foundation model.

[!TIP] After completing any fine-tuning, always register the new model with register_model so it can be reused in future tasks.