An alternative derivation of the equations of motion in torsion space for a branched linear chain

Torsion space molecular dynamics may be more efficiently encoded if the global motions are separated from the internal motions. The equations of motion for single, non-cyclic chains are shown to be first order in the backbone angle parameters when the global frame of reference is ignored and second order otherwise. Adding a simple heuristic substitute for the global motions enables the encoding of dynamics for mixed constrained/unconstrained model systems.