Method & caveats

The DFT reference is each structure's Materials-Project cell (the relaxation input cell); the MLIP relaxes cell shape + volume to its own equilibrium. The headline median |Δ edge| is the median over structures of the mean absolute % error of the three cell-edge lengths (sorted-matched, basis-invariant); median strain ‖E‖ is the rotation-invariant Green–Lagrange strain norm, which also captures shear/angle errors. Medians tame heavy tails. Full protocol and metric definitions: Lattice-constants methodology →.