Bond-Angle Distributions (ADF)

The angular distribution function counts, for every atom, the angle subtended at it by each pair of its bonded neighbours. Splitting by triplet type separates the coordination environments: a silicate shows a sharp tetrahedral O-Si-O peak near 109.5° alongside a much broader Si-O-Si linkage distribution. Angles that close through a periodic boundary are included — the cell is expanded with image atoms before the bond search, so boundary atoms are not under-coordinated.