Related Experiment Video
Updated: Jun 25, 2025
09:32
Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
8.2K
Emergent facilitation and glassy dynamics in supercooled liquids
Muhammad R Hasyim1, Kranthi K Mandadapu1,2
1Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720.
Summary
This study reveals how localized bond-exchange events, or excitations, drive dynamical facilitation in supercooled liquids. Elastic interactions between these excitations explain complex glassy relaxation dynamics and super-Arrhenius temperature dependence.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Statistical Mechanics
Background:
- Supercooled liquids exhibit complex dynamics, including spatially heterogeneous motion and super-Arrhenius relaxation, phenomena attributed to dynamical facilitation.
- Dynamical facilitation, where local motion triggers further motion, is crucial for understanding glassy relaxation but lacks a clear theoretical origin.
- Existing models struggle to explain the microscopic mechanisms driving facilitation and its impact on relaxation timescales.
Purpose of the Study:
- To develop a theoretical framework explaining the microscopic origins of dynamical facilitation in supercooled liquids.
- To elucidate how localized events and their interactions govern the emergent properties of glassy dynamics.
- To connect theoretical predictions with experimental and simulation observations of supercooled liquid behavior.
Main Methods:
- Developed a theory based on localized bond-exchange events (excitations) and their elastic interactions.
- Utilized the theory of linear elasticity and Markov processes to model the system.
- Simulated a model that incorporates elastic stresses and excitation interactions.
Main Results:
- The model reproduces key aspects of glassy dynamics: stretched exponential relaxation, super-Arrhenius scaling of relaxation times, and 2D finite-size effects.
- Predicted subdiffusive behavior in the mean squared displacement (MSD) at short and intermediate timescales.
- Derived phonon contributions, which, combined with excitation contributions, explain two-step relaxation and ballistic-subdiffusive-diffusive MSD crossovers.
Conclusions:
- The theory successfully explains the emergence of dynamical facilitation from localized bond-exchange events and elastic interactions.
- The model provides a unified framework for understanding diverse phenomena in supercooled liquids, from relaxation dynamics to MSD behavior.
- This work offers a microscopic basis for dynamical facilitation, advancing the understanding of glassy states.
Related Concept Videos
02:39Phase Transitions: Melting and Freezing
12.4K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
12.4K
01:25Crystal Growth: Principles of Crystallization
1.8K
Crystallization is a phase transformation process in which crystals are precipitated from a supersaturated solution or formed from other sources. During crystallization, atoms or molecules arrange themselves into a well-defined, rigid crystal lattice to minimize energy.
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent...
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent...
1.8K
01:10Recrystallization: Solid–Solution Equilibria
1.1K
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...
1.1K
01:34The Fluid Mosaic Model
146.9K
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.
146.9K
02:57Surface Tension, Capillary Action, and Viscosity
27.7K
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
27.7K
02:54Molecular and Ionic Solids
17.1K
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
17.1K