Equilibrium binding energies from fluctuation theorems and force spectroscopy simulations

Hodges, Emma, Cooke, B. M., Sevick E.M., Searles, Debra J., Dunweg, B. and Prakash, J. Ravi (2016) Equilibrium binding energies from fluctuation theorems and force spectroscopy simulations. Soft Matter, 12 48: 9803-9820. doi:10.1039/C6SM02549H

Author Hodges, Emma
Cooke, B. M.
Sevick E.M.
Searles, Debra J.
Dunweg, B.
Prakash, J. Ravi
Title Equilibrium binding energies from fluctuation theorems and force spectroscopy simulations
Journal name Soft Matter   Check publisher's open access policy
ISSN 1744-6848
Publication date 2016-11-14
Year available 2016
Sub-type Article (original research)
DOI 10.1039/C6SM02549H
Open Access Status Not yet assessed
Volume 12
Issue 48
Start page 9803
End page 9820
Total pages 18
Place of publication Cambridge, United Kingdom
Publisher Royal Society of Chemistry
Language eng
Formatted 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.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

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