Length Scales in Brownian yet Non-Gaussian Dynamics

According to the classical theory of Brownian motion, the mean-squared displacement of diffusing particles evolves linearly with time, whereas the distribution of their displacements is Gaussian. However, recent experiments on mesoscopic particle systems have discovered Brownian yet non-Gaussian reg...

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Autores principales:	José M. Miotto, Simone Pigolotti, Aleksei V. Chechkin, Sándalo Roldán-Vargas
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/39e94b29a290409788c79ef30545653c
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spelling	oai:doaj.org-article:39e94b29a290409788c79ef30545653c2021-12-02T16:19:17ZLength Scales in Brownian yet Non-Gaussian Dynamics10.1103/PhysRevX.11.0310022160-3308https://doaj.org/article/39e94b29a290409788c79ef30545653c2021-07-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.031002http://doi.org/10.1103/PhysRevX.11.031002https://doaj.org/toc/2160-3308According to the classical theory of Brownian motion, the mean-squared displacement of diffusing particles evolves linearly with time, whereas the distribution of their displacements is Gaussian. However, recent experiments on mesoscopic particle systems have discovered Brownian yet non-Gaussian regimes where diffusion coexists with an exponential tail in the distribution of displacements. Here we show that, contrary to the present theoretical understanding, the length scale λ associated with this exponential distribution does not necessarily scale in a diffusive way. Simulations of Lennard-Jones systems reveal a behavior λ∼t^{1/3} in three dimensions and λ∼t^{1/2} in two dimensions. We propose a scaling theory based on the idea of hopping motion to explain this result. In contrast, simulations of a tetrahedral gelling system, where particles interact by a nonisotropic potential, yield a temperature-dependent scaling of λ. We interpret this behavior in terms of an intermittent hopping motion. Our findings link the Brownian yet non-Gaussian phenomenon with generic features of glassy dynamics and open new experimental perspectives on the class of molecular and supramolecular systems whose dynamics is ruled by rare events.José M. MiottoSimone PigolottiAleksei V. ChechkinSándalo Roldán-VargasAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 3, p 031002 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 José M. Miotto Simone Pigolotti Aleksei V. Chechkin Sándalo Roldán-Vargas Length Scales in Brownian yet Non-Gaussian Dynamics
description	According to the classical theory of Brownian motion, the mean-squared displacement of diffusing particles evolves linearly with time, whereas the distribution of their displacements is Gaussian. However, recent experiments on mesoscopic particle systems have discovered Brownian yet non-Gaussian regimes where diffusion coexists with an exponential tail in the distribution of displacements. Here we show that, contrary to the present theoretical understanding, the length scale λ associated with this exponential distribution does not necessarily scale in a diffusive way. Simulations of Lennard-Jones systems reveal a behavior λ∼t^{1/3} in three dimensions and λ∼t^{1/2} in two dimensions. We propose a scaling theory based on the idea of hopping motion to explain this result. In contrast, simulations of a tetrahedral gelling system, where particles interact by a nonisotropic potential, yield a temperature-dependent scaling of λ. We interpret this behavior in terms of an intermittent hopping motion. Our findings link the Brownian yet non-Gaussian phenomenon with generic features of glassy dynamics and open new experimental perspectives on the class of molecular and supramolecular systems whose dynamics is ruled by rare events.
format	article
author	José M. Miotto Simone Pigolotti Aleksei V. Chechkin Sándalo Roldán-Vargas
author_facet	José M. Miotto Simone Pigolotti Aleksei V. Chechkin Sándalo Roldán-Vargas
author_sort	José M. Miotto
title	Length Scales in Brownian yet Non-Gaussian Dynamics
title_short	Length Scales in Brownian yet Non-Gaussian Dynamics
title_full	Length Scales in Brownian yet Non-Gaussian Dynamics
title_fullStr	Length Scales in Brownian yet Non-Gaussian Dynamics
title_full_unstemmed	Length Scales in Brownian yet Non-Gaussian Dynamics
title_sort	length scales in brownian yet non-gaussian dynamics
publisher	American Physical Society
publishDate	2021
url	https://doaj.org/article/39e94b29a290409788c79ef30545653c
work_keys_str_mv	AT josemmiotto lengthscalesinbrownianyetnongaussiandynamics AT simonepigolotti lengthscalesinbrownianyetnongaussiandynamics AT alekseivchechkin lengthscalesinbrownianyetnongaussiandynamics AT sandaloroldanvargas lengthscalesinbrownianyetnongaussiandynamics
_version_	1718384163493511168

Length Scales in Brownian yet Non-Gaussian Dynamics

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