TY  - JOUR
A1  - Krüsemann, Henning
A1  - Godec, Aljaz
A1  - Metzler, Ralf
T1  - First-passage statistics for aging diffusion in systems with annealed and quenched disorder
JF  - Physical review : E, Statistical, nonlinear and soft matter physics
N2  - Aging, the dependence of the dynamics of a physical process on the time t(a) since its original preparation, is observed in systems ranging from the motion of charge carriers in amorphous semiconductors over the blinking dynamics of quantum dots to the tracer dispersion in living biological cells. Here we study the effects of aging on one of the most fundamental properties of a stochastic process, the first-passage dynamics. We find that for an aging continuous time random walk process, the scaling exponent of the density of first-passage times changes twice as the aging progresses and reveals an intermediate scaling regime. The first-passage dynamics depends on t(a) differently for intermediate and strong aging. Similar crossovers are obtained for the first-passage dynamics for a confined and driven particle. Comparison to the motion of an aged particle in the quenched trap model with a bias shows excellent agreement with our analytical findings. Our results demonstrate how first-passage measurements can be used to unravel the age t(a) of a physical system.
Y1  - 2014
U6  - https://doi.org/10.1103/PhysRevE.89.040101
SN  - 1539-3755
SN  - 1550-2376
VL  - 89
IS  - 4
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Godec, Aljaz
A1  - Chechkin, Aleksei V.
A1  - Barkai, Eli
A1  - Kantz, Holger
A1  - Metzler, Ralf
T1  - Localisation and universal fluctuations in ultraslow diffusion processes
JF  - Journal of physics : A, Mathematical and theoretical
N2  - We study ultraslow diffusion processes with logarithmic mean squared displacement (MSD) < x(2)(t)> similar or equal to log(gamma)t. Comparison of annealed (renewal) continuous time random walks (CTRWs) with logarithmic waiting time distribution psi(tau) similar or equal to 1/(tau log(1+gamma)tau) and Sinai diffusion in quenched random landscapes reveals striking similarities, despite the great differences in their physical nature. In particular, they exhibit a weakly non-ergodic disparity of the time-averaged and ensemble-averaged MSDs. Remarkably, for the CTRW we observe that the fluctuations of time averages become universal, with an exponential suppression of mobile trajectories. We discuss the fundamental connection between the Golosov localization effect and non-ergodicity in the sense of the disparity between ensemble-averaged MSD and time-averaged MSD.
KW  - Sinai diffusion
KW  - anomalous diffusion
KW  - quenched energy landscape
Y1  - 2014
U6  - https://doi.org/10.1088/1751-8113/47/49/492002
SN  - 1751-8113
SN  - 1751-8121
VL  - 47
IS  - 49
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Godec, Aljaz
A1  - Bauer, Maximilian
A1  - Metzler, Ralf
T1  - Collective dynamics effect transient subdiffusion of inert tracers in flexible gel networks
JF  - New journal of physics : the open-access journal for physics
N2  - Based on extensive Brownian dynamics simulations we study the thermal motion of a tracer bead in a cross-linked, flexible gel in the limit when the tracer particle size is comparable to or even larger than the equilibrium mesh size of the gel. The analysis of long individual trajectories of the tracer demonstrates the existence of pronounced transient anomalous diffusion. From the time averaged mean squared displacement and the time averaged van Hove correlation functions we elucidate the many-body origin of the non-Brownian tracer bead dynamics. Our results shed new light onto the ongoing debate over the physical origin of steric tracer interactions with structured environments.
KW  - anomalous diffusion
KW  - gel network
KW  - van Hove correlation
Y1  - 2014
U6  - https://doi.org/10.1088/1367-2630/16/9/092002
SN  - 1367-2630
VL  - 16
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Bauer, Maximilian
A1  - Godec, Aljaz
A1  - Metzler, Ralf
T1  - Diffusion of finite-size particles in two-dimensional channels with random wall configurations
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Diffusion of chemicals or tracer molecules through complex systems containing irregularly shaped channels is important in many applications. Most theoretical studies based on the famed Fick-Jacobs equation focus on the idealised case of infinitely small particles and reflecting boundaries. In this study we use numerical simulations to consider the transport of finite-size particles through asymmetrical two-dimensional channels. Additionally, we examine transient binding of the molecules to the channel walls by applying sticky boundary conditions. We consider an ensemble of particles diffusing in independent channels, which are characterised by common structural parameters. We compare our results for the long-time effective diffusion coefficient with a recent theoretical formula obtained by Dagdug and Pineda
Y1  - 2014
U6  - https://doi.org/10.1039/c3cp55160a
SN  - 1463-9076
SN  - 1463-9084
VL  - 16
IS  - 13
SP  - 6118
EP  - 6128
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -