Comment on `Checking the influence of numerically induced chaos in the computational study of intramolecular dynamics using trajectory equivalenceʹ

The interpretation of a recent molecular dynamics study of equivalent trajectories is questioned. It is shown by a simple counter-example that the observed sudden damping of modes can be explained by a simple dephasing effect due to round-off error, rather than numerical chaos due to coupling terms in the Hamiltonian. The effect can be eliminated by a simple change to the averaging procedure.