Do internal degrees of freedom trigger or destroy superdiffusive jumps in molecular diffusion?

by Sarah Hallerberg (Max Planck Institute Göttingen, Germany)

Tuesday 19 Jun 2012, 13:30 → 14:30 Europe/Stockholm

122:026

Long jumps in surface diffusion of organic molecules and nanoscale clusters have been observed experimentally, and were also found in numerical simulations. Recent studies highlight the existence of a relation between the diffusion of molecules and the dynamics of their internal degrees of freedom. These internal chaotic dynamics lead to normal diffusion, even in the absence of thermal noise. Our contribution aims at determining the physical mechanism which trigger long superdiffusive jumps. Benzene on graphite is a prototype system and serves us to investigate these long jumps by postprocessing the output of atomistic simulations. In more detail, we search for precursors in the internal degrees of freedom by considering the energy in the vibrational modes of the linearised system and show that relevant precursors appear particularly in the torsional vibrations. Our results suggest a strong connection between lack of torsion of the molecule and long superdiffusive jumps.