# Regensburg 2013 – wissenschaftliches Programm

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# DY: Fachverband Dynamik und Statistische Physik

## DY 7: Poster I

### DY 7.9: Poster

### Montag, 11. März 2013, 17:30–19:30, Poster C

**Improved modelling of forced Kramers escape** — •Jakob Tómas Bullerjahn, Sebastian Sturm, and Klaus Kroy — Universität Leipzig, Faculty of Physics & Earth Sciences, Institute for Theoretical Physics, Brüderstr. 16, 04103 Leipzig, Germany

The forcible separation of non-covalent bonds, such as in protein unfolding and ligand dissociation, can be regarded as a transition between a bound and an unbound state [1]. This two-state system can be modelled by a test particle moving in an effective free energy landscape, trying to overcome an energy barrier separating the two states. Due to external loading the unbound state is favoured, which makes the escape practically irreversible. However, established models of such forced rupture [1,2] are restricted to the adiabatic limit of small loading rates, thus making it impossible to apply them to all-atom simulations.

Starting from the test particle's equation of motion, we describe its irreversible escape from a potential well, driven by a time-dependent external force protocol. Our model is analytically tractable and yields an expression for the rupture force distribution measured in dynamic force spectroscopy experiments [3], which holds for small and large loading rates alike. It can be extended to non-Markovian processes with arbitrary memory kernels and reduces to the main result of [2] in the limit of small loading rates.

[1] E. Evans & K. Ritchie, Biophys.J. 72, 1541 (1997) [2] O. K. Dudko, G. Hummer & A. Szabo, Phys. Rev. Lett. 96, 108101 (2006) [3] M. Carrion-Vazquez, et al., Proc. Natl. Acad. Sci. 96, 3694 (1999)