Equilibrium binding energies from fluctuation theorems and force spectroscopy simulations. Issue 48 (18th November 2016)

• Record Type: Journal Article
• Authors: Hodges, Emma; Cooke, B. M.; Sevick, E. M.; Searles, Debra J.; Dünweg, B.; Prakash, J. Ravi
• Is Part Of: Soft matter. Volume 12:Issue 48(2016)
• Page Start: 9803
• Page End: 9820
• Publication Date: 2016-11-18
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c6sm02549h
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Brownian dynamics simulations are used to study the detachment of a particle from a substrate. Abstract : Brownian dynamics simulations are used to study the detachment of a particle from a substrate. Although the model is simple and generic, we attempt to map its energy, length and time scales onto a specific experimental system, namely a bead that is weakly bound to a cell and then removed by an optical tweezer. The external driving force arises from the combined optical tweezer and substrate potentials, and thermal fluctuations are taken into account by a Brownian force. The Jarzynski equality and Crooks fluctuation theorem are applied to obtain the equilibrium free energy difference between the final and initial states. To this end, we sample non-equilibrium work trajectories for various tweezer pulling rates. We argue that this methodology should also be feasible experimentally for the envisioned system. Furthermore, we outline how the measurement of a whole free energy profile would allow the experimentalist to retrieve the unknown substrate potential by means of a suitable deconvolution. The influence of the pulling rate on the accuracy of the results is investigated, and umbrella sampling is used to obtain the equilibrium probability of particle escape for a variety of trap potentials.