Ackland-Jones Analysis

Ackland-Jones Analysis assigns each atom a structure type (FCC, HCP, BCC, ICO, or OTHER) from the bond-angle distribution of its nearest neighbors (Ackland & Jones, PRB 2006). The neighbor shell is determined adaptively from the local mean squared distance, so classification is fully parameter-free.

Parameters

This plugin takes no parameters — structure classification is adaptive and parameter-free. Just point it at a trajectory.

Output

The plugin writes two parquet files per frame.

{outputBase}_atoms.parquet

Per-atom data in AtomisticExporter format, consumed by the VOLT viewer for 3D rendering. Atoms are grouped into buckets keyed by structure name (FCC, HCP, BCC, ICO, OTHER).

interface Atom {
    id: int;
    pos: [float, float, float];
    structure_id: int;
    structure_name: string;       // "FCC" | "HCP" | "BCC" | "ICO" | "OTHER"
    cluster_id: int;
    structure_type: int;          // 0 OTHER | 1 FCC | 2 HCP | 3 BCC | 4 ICO
}

interface AtomsOutput {
    main_listing: {
        total_atoms: int;
        structure_count: int;
    };
    sub_listings: {
        structures: Array<{
            structure_id: int;
            structure_name: string;
            atom_count: int;
        }>;
    };
    export: {
        AtomisticExporter: {
            [bucketName: string]: Atom[];
        };
    };
}

Surfaced in VOLT as the Ackland-Jones Structure exposure and exported as a .glb scene.

{outputBase}_ackland_jones.parquet

Per-frame summary of the structure-type counts (listing-only — no per-atom sub-listing).

interface AcklandJonesSummary {
    main_listing: {
        total_atoms: int;
        OTHER: int;
        FCC: int;
        HCP: int;
        BCC: int;
        ICO: int;
    };
}

See Also

• Adaptive Common Neighbor Analysis — CNA-based structure classifier that also emits DXA cluster-graph artifacts
• Polyhedral Template Matching — robust structure classifier that additionally handles simple-cubic and icosahedral environments
• Centrosymmetry Parameter — continuous per-atom disorder measure for the same defect-identification workflows