Fickian crossover and lengthscales from two point functions in supercooled liquids
arXiv:cond-mat/0509600 · doi:10.1063/1.2221309
Abstract
Particle motion of a Lennard-Jones supercooled liquid near the glass transition is studied by molecular dynamics simulations. We analyze the wave vector dependence of relaxation times in the incoherent self scattering function and show that at least three different regimes can be identified and its scaling properties determined. The transition from one regime to another happens at characteristic length scales. The lengthscale associated with the onset of Fickian diffusion corresponds to the maximum size of heterogeneities in the system, and the characterisitic timescale is several times larger than the alpha relaxation time. A second crossover lengthscale is observed, which corresponds to the typical time and length of heterogeneities, in agreement with results from four point functions. The different regimes can be traced back in the behavior of the van Hove distribution of displacements, which shows a characteristic exponential regime in the heterogeneous region before the crossover to gaussian diffusion and should be observable in experiments. Our results show that it is possible to obtain characteristic length scales of heterogeneities through the computation of two point functions at different times.
to appear in J. Chem. Phys (2006)
References in corpus (17)
- Direct experimental evidence of a growing length scale accompanying the glass transition
- Glassy dynamics of kinetically constrained models
- Geometrical explanation and scaling of dynamical heterogeneities in glass forming systems
- What do we learn from the shape of the dynamical susceptibility of glass-formers?
- Excitation lines and the breakdown of Stokes-Einstein relations in supercooled liquids
- Time and length scales in supercooled liquids
- Length scale for the onset of Fickian diffusion in supercooled liquids
- Dynamic criticality in glass-forming liquids
- Real space origin of temperature crossovers in supercooled liquids
- Dynamical heterogeneities close to a colloidal gel
- What does the potential energy landscape tell us about the dynamics of supercooled liquids and glasses?
- Particle rearrangements during transitions between local minima of the potential energy landscape of a supercooled Lennard-Jones liquid
- Relaxation in a glassy binary mixture: Mode-coupling-like power laws, dynamic heterogeneity and a new non-Gaussian parameter
- General features of the energy landscape in Lennard-Jones like model liquids
- The distance between Inherent Structures and the influence of saddles on approaching the mode coupling transition in a simple glass former
- Time correlation functions between Inherent Structures: a connection between landscape topology and the dynamics of glassy systems
- Inherent structures dynamics in glasses: a comparative study
Cited by in corpus (14)
- Dynamics on the Way to Forming Glass: Bubbles in Space-time
- Universal nature of particle displacements close to glass and jamming transitions
- De-coupling of Exchange and Persistence Times in Atomistic Models of Glass Formers
- A random walk description of the heterogeneous glassy dynamics of attracting colloids
- Dynamical Heterogeneity in Lattice Glass Models
- Dynamical heterogeneity in a model for permanent gels: Different behavior of dynamical susceptibilities
- From coupled elementary units to the complexity of the glass transition
- Aging in Dense Colloids as Diffusion in the Logarithm of Time
- Driving kinetically constrained models into non-equilibrium steady states: structural and slow transport properties
- Active cage model of glassy dynamics
- Emergence of complex behavior in gelling systems starting from simple behavior of single clusters
- Properties of ideal Gaussian glass-forming systems
- Two-Time Correlations for Probing the Aging Dynamics of Jammed Colloids
- ShearView: A Compact Stress- and Strain-Controlled Rheometer for Integrated Rheo-microscopy