Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions

We introduce new Langevin-type equations describing the rotational and translational motion of rigid bodies interacting through conservative and non-conservative forces, and hydrodynamic coupling. In the absence of non-conservative forces the Langevin-type equations sample from the canonical ensembl...

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Main Authors: Davidchack, R.L., Ouldridge, T.E., Tretyakov, M.V.
Format: Article
Published: American Institute of Physics 2017
Subjects:
Online Access:https://eprints.nottingham.ac.uk/48725/
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author Davidchack, R.L.
Ouldridge, T.E.
Tretyakov, M.V.
author_facet Davidchack, R.L.
Ouldridge, T.E.
Tretyakov, M.V.
author_sort Davidchack, R.L.
building Nottingham Research Data Repository
collection Online Access
description We introduce new Langevin-type equations describing the rotational and translational motion of rigid bodies interacting through conservative and non-conservative forces, and hydrodynamic coupling. In the absence of non-conservative forces the Langevin-type equations sample from the canonical ensemble. The rotational degrees of freedom are described using quaternions, the lengths of which are exactly preserved by the stochastic dynamics. For the proposed Langevin-type equations, we construct a weak 2nd order geometric integrator which preserves the main geometric features of the continuous dynamics. The integrator uses Verlet-type splitting for the deterministic part of Langevin equations appropriately combined with an exactly integrated Ornstein-Uhlenbeck process. Numerical experiments are presented to illustrate both the new Langevin model and the numerical method for it, as well as to demonstrate how inertia and the coupling of rotational and translational motion can introduce qualitatively distinct behaviours.
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spelling nottingham-487252020-05-04T19:22:08Z https://eprints.nottingham.ac.uk/48725/ Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions Davidchack, R.L. Ouldridge, T.E. Tretyakov, M.V. We introduce new Langevin-type equations describing the rotational and translational motion of rigid bodies interacting through conservative and non-conservative forces, and hydrodynamic coupling. In the absence of non-conservative forces the Langevin-type equations sample from the canonical ensemble. The rotational degrees of freedom are described using quaternions, the lengths of which are exactly preserved by the stochastic dynamics. For the proposed Langevin-type equations, we construct a weak 2nd order geometric integrator which preserves the main geometric features of the continuous dynamics. The integrator uses Verlet-type splitting for the deterministic part of Langevin equations appropriately combined with an exactly integrated Ornstein-Uhlenbeck process. Numerical experiments are presented to illustrate both the new Langevin model and the numerical method for it, as well as to demonstrate how inertia and the coupling of rotational and translational motion can introduce qualitatively distinct behaviours. American Institute of Physics 2017-12-12 Article PeerReviewed Davidchack, R.L., Ouldridge, T.E. and Tretyakov, M.V. (2017) Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions. Journal of Chemical Physics, 147 (22). 224103/1- 224103/131. ISSN 1089-7690 rigid body dynamics; quaternions; hydrodynamic interactions; Stokesian dynamics; canonical ensemble; Langevin equations; stochastic differential equations; weak approximation; ergodic limits; stochastic geometric integrators http://aip.scitation.org/doi/full/10.1063/1.4999771 doi:10.1063/1.4999771 doi:10.1063/1.4999771
spellingShingle rigid body dynamics; quaternions; hydrodynamic interactions; Stokesian dynamics; canonical ensemble; Langevin equations; stochastic differential equations; weak approximation; ergodic limits; stochastic geometric integrators
Davidchack, R.L.
Ouldridge, T.E.
Tretyakov, M.V.
Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
title Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
title_full Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
title_fullStr Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
title_full_unstemmed Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
title_short Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
title_sort geometric integrator for langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
topic rigid body dynamics; quaternions; hydrodynamic interactions; Stokesian dynamics; canonical ensemble; Langevin equations; stochastic differential equations; weak approximation; ergodic limits; stochastic geometric integrators
url https://eprints.nottingham.ac.uk/48725/
https://eprints.nottingham.ac.uk/48725/
https://eprints.nottingham.ac.uk/48725/