Dresden 2011 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 26: Nonlinear Dynamics II

DY 26.1: Talk

Wednesday, March 16, 2011, 16:30–16:45, ZEU 255

Nonlinear dynamics of the internal degrees of freedom and transport of benzene on graphite — •Astrid S. de Wijn — IMM, Radboud University Nijmegen, the Netherlands

The presence of internal degrees of freedom has been connected to the diffusion and friction of molecules on surfaces. In this work, the chaotic internal degrees of freedom of a benzene molecule adsorbed on a graphite substrate [1], their interplay with thermal noise, and their effects on the diffusion and friction are investigated analytically and numerically by making use of the presence of two different time scales. It is found that that the substrate temperature affects the dynamics of the internal degrees of freedom only weakly, yet still influences the friction and diffusion.

The contributions from different degrees of freedom to diffusion and friction are identified analytically and numerically and found to be sufficiently large to account for the high friction found in experiments [2]. In atomistic molecular dynamics simulations of the system, various internal degrees of freedom can be investigated separately. Torsion of the benzene molecule dominates the chaotic dynamics and the effects of the internal degrees of freedom on the diffusion and friction. Based on the analytical and numerical results, suggestions are made for experimental conditions under which the effects of internal degrees of freedom might be more directly observable.

[1] A. S. de Wijn and A. Fasolino, Journal of Physics: Condensed Matter, 21, 264002 (2009).

[2] H. Hedgeland, er al., Nature Physics, 5, 561 (2009).