Nonlinear response from the perspective of energy landscapes

• Applicant: Professor Dr. Andreas Heuer
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2010 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 157463299

The complexity of the dynamics of supercooled liquids is largely related to the highly cooperative dynamics which is required to achieve structural relaxation. It is planned to study the non-linear response of probe particles via molecular dynamics simulations to unravel some key aspects of this cooperativity. As a model system we take the well-studied binary Lennard-Jones system. Beyond the determination of standard observables such as the van Hove correlation function the results shall be expressed in terms of the framework of the potential energy landscape as well as of continuous time random walk characteristics. Both approaches have proven to be very helpful to gain a better understanding of the equilibrium case. Starting from this well-founded basis we study the different regimes of forced motion, starting from linear response via weakly non-linear effects to very strong forces with individual characteristics for each regime. A closer understanding is further attempted by studying the structure and dynamics of the neighborhood of the forced probe particles. In a next step this project will be extended, on the one hand, by studying the effective attractive interaction of probe particles and, on the other hand, by analyzing the effect of oscillating forces. Finally, based on these ingredients we will perform a detailed comparison of our Lennard-Jones results with corresponding experiments by the Roling group on mixtures of ionic liquids and molecules.

• DFG Programme: Research Units
• Subproject of: FOR 1394: Nonlinear Response to Probe Vitrification