  We review two standard methods for structural classification in simulations
of crystalline phases, the Common Neighbour Analysis and the Centrosymmetry
Parameter. We explore the definitions and implementations of each of their
common variants, and investigate their respective failure modes and
classification biases. Simple modifications to both methods are proposed, which
improve their robustness, interpretability, and applicability. We denote these
variants the Interval Common Neighbour Analysis, and the Minimum-Weight
Matching Centrosymmetry Parameter.
