It was recalled that chaotic internal degrees of freedom of a molecule could act as noise and affect the diffusion of the molecule on a substrate. A separation of time-scales between the fast internal dynamics and the slow motion of the centre of mass on the substrate made it possible to link chaos directly to diffusion. The conditions under which this was possible were considered and it was shown that, in simple atomistic models with pair-wise harmonic potentials, strong chaos could arise from the geometry Using molecular dynamics simulations, it was demonstrated that a realistic model of benzene was indeed chaotic, and that the internal chaos affected its diffusion on a graphite substrate.

Relating Chaos to Deterministic Diffusion of a Molecule Adsorbed on a Surface. A.S.de Wijn, A.Fasolino: Journal of Physics - Condensed Matter, 2009, 21[26], 264002