Architecture

The host supplies the potential surface and owns the outer search loop. rgsaddle supplies band force assembly, minimum-mode rotation, restricted index-1 steps, Sella sessions, intrinsic reaction coordinate integration and molecular dynamics mechanics.

Band and minimum-mode translation use rgmin’s solver. Dense quadratic restriction is available through rgsaddle::trust, which re-exports rgmin’s dense controller. The root rgsaddle::TrustRegion accepts a spectrum for Sella steps. The projected band trust method is implemented by BandRtr.

PointSurface accepts one coordinate vector. BandSurface accepts a collection of images. The C callback expresses either request with the same official structure. The library has no Message Passing Interface (MPI) dependency; a host can evaluate a request collectively or distribute image work itself.

Hessian storage and updates live in pes and qn. linalg supplies numerical actions and cached direction/action pairs. eigensolve supplies dense and iterative eigenproblems. sparse_hessian builds a cutoff Hessian by a direct Curtis-Powell-Reid partition of a distance-2 colouring and implements ApplyHessian. Molecular topology enters through vocn and the equality chart. Periodic differences use linkcell.