Stochastic theory of barrier-crossing processes under large thermal fluctuations

Lead Research Organisation: University of Cambridge
Department Name: Chemical Engineering and Biotechnology

Abstract

Formation of bonds in thermally agitated environments is ubiquitous in biological, solid state, and nuclear physics with many engineering applications. Particles or molecular associations form binary complexes when there is an energy gain upon forming a bond. Examples include nanoparticle absorption to membranes, protein-ligand bindings, and atomic force microscopy (AFM) studies of the cellular membrane. The energy gain upon forming the bond, i.e. the binding energy Q, also determines the bond's stability in an environment with thermal fluctuations. When the binding energy is small compared to thermal fluctuations that have energies of the order kBT, i.e. when Q= kBT ~ 1, the bond is unstable and can break on a short time scale. Conversely, for large binding energies, Q >> kBT, the bond is stable, and the dissociation time is very long. Current theories are successful in the latter case of large binding energy, but fail completely in the opposite limit of low energy/large thermal fluctuations. The goal of this PhD is to fill this gap in our understanding of thermally-activated dissociation processes. Stochastic methods will be employed and combined creatively with Zwanzig-Caldeira-Leggett system-bath Hamiltonian methods to properly describe the role of friction. The theory will be applied to selected important problems such as biomolecular receptor-ligand binding, biological filament dissociation, and alike.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509620/1 30/09/2016 29/09/2022
1778174 Studentship EP/N509620/1 30/09/2016 29/06/2021 Thomas Gray
EP/R513180/1 30/09/2018 29/09/2023
1778174 Studentship EP/R513180/1 30/09/2016 29/06/2021 Thomas Gray
 
Description Research into diffusion and sub-diffusion in piecewise-defined potential energy landscapes 
Organisation Nanyang Technological University
Country Singapore 
Sector Academic/University 
PI Contribution Intellectual input - I researched the literature, developed the relevant theory, and performed the numerical simulations required in order to test it.
Collaborator Contribution Resources - time on the machines at the NTU High-Performance Computing Centre. Intellectual input - time spent discussing my research and theory.
Impact One paper has been accepted by Physical Review E and will be published in the near future. We are currently working towards a second paper.
Start Year 2018