Ackland-Jones Analysis
Classify FCC, HCP, BCC and icosahedral atoms from the distribution of bond angles to their nearest neighbors, with no cutoff to set.
Ackland-Jones analysis classifies each atom from the angles between the bonds to its nearest neighbors. It needs no cutoff and no parameters, which makes it a quick first look at a metal's crystal structure, including icosahedral order in liquids and glasses.
| Key | Version | Builds |
|---|---|---|
ackland-jones | 1.1.1 | Linux, macOS, Windows, browser |
How it works
For each atom the plugin takes its 14 nearest neighbors and sets a local length scale r₀² from the mean squared distance of the six closest. The neighbors whose squared distance is under 1.45 r₀² form the shell. It sorts the cosines of all bond angles in the shell into eight bins, and compares the bin counts with those of ideal FCC, HCP, BCC and icosahedral environments. The closest match wins; an atom with angles in the last bin, or no clear match, is OTHER.
Inputs
- Atom positions and the simulation cell.
Arguments
This plugin has no arguments.
Outputs
| Exposure | What you get |
|---|---|
| Ackland-Jones Structure | A listing, and a 3D model of the atoms colored by structure: OTHER, FCC, HCP, BCC, ICO. |
| Ackland-Jones Summary | The frame's totals: atoms, and atoms per structure. Stored with the analysis. No listing. |
The workflow declares one per-atom property, structure_type (Structure Type), with the values 0 OTHER, 1 FCC, 2 HCP, 3 BCC, 4 ICO.
Notes
- Ackland-Jones doesn't produce the cluster tables OpenDXA needs. For dislocation analysis, use Polyhedral Template Matching or Adaptive Common Neighbor Analysis.
Reference
G. J. Ackland, A. P. Jones, "Applications of local crystal structure measures in experiment and simulation", Phys. Rev. B 73, 054104 (2006).