MACE Committee Model Uncertainty Quantification

Goal

To estimate the epistemic uncertainty of a MACE MLIP by running inference with a committee (ensemble) of independently trained models. Structures where the committee disagrees strongly (high energy or force variance) are flagged as candidates for DFT labelling, supporting active learning workflows and validating MLIP reliability in under-sampled regions of configuration space.

The uncertainty estimate is:

• Energy uncertainty: standard deviation of predicted energies across committee members (meV/atom)
• Force uncertainty: component-wise force RMSE of the across-committee standard deviations (meV/Å): take the sample standard deviation for every atom and Cartesian component, then take one root-mean-square over all 3N components. This is the conventional MLIP force-RMSE reduction used by MACE reporting.

[!WARNING] Energy std is only a valid disagreement signal when every committee member shares the same energy reference — the same training dataset, level of theory, and atomic reference energies (E0). If the committee instead pools several independently pretrained foundation models (e.g. different MACE-MP / MACE-OMAT / MACE-MATPES releases) rather than same-data/different-seed checkpoints, their absolute energies are not on a common scale: an energy-std ranking will mostly reflect per-model reference-energy offsets, not genuine epistemic disagreement. For this heterogeneous committee flavor, rank structures by force disagreement instead — forces are invariant to each model's arbitrary atomic reference energy, so they remain a reliable cross-model signal. See the heterogeneous-committee note under Constraints.

Instructions

1. Obtain Committee Models