← Algorithms · Ab initio bead model (DAM)

Ab initio bead model (DAM)

Purpose. Recover a low-resolution molecular envelope without assuming a geometric primitive. Dummy-atom models (DAMs) place beads in space so that their scattering matches the experimental curve (within the information content of SAXS). Useful when shape is unknown but the sample is reasonably monodisperse and p(r) is trustworthy.

Engine. ATSAS DAMMIF (fast/slow annealing). When several independent runs are requested, DAMAVER aligns models and builds an averaged occupancy / “most probable” representation.

What autosaxs adds.

1. Requires a GNOM/DATGNOM .out from fit_distances (runs it in-process if missing).
2. Launches n_runs DAMMIF replicas; for n_runs > 1, runs DAMAVER and exports a consensus CIF / occupancy view.
3. Computes per-replica Monte Carlo bead-pair p(r) curves for comparison with the GNOM distribution, and supports overlap visualization in liveview.

Autosaxs does not invent a new reconstruction algorithm — it standardizes the Grant/ATSAS workflow and QC artifacts for automated TIFF processing.

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