Related Experiment Video
Updated: Jan 20, 2026
02:31
Phase Transitions and Effect of Intermolecular Forces
22.6K
Scalar activity induced phase separation and liquid-solid transition in a Lennard-Jones system
S Siva Nasarayya Chari1, Chandan Dasgupta, Prabal K Maiti
1Department of Physics, Indian Institute of Science, C. V. Raman Ave, Bengaluru 560012, India. ssnchari@gmail.com cdgupta@iisc.ac.in maiti@iisc.ac.in.
Soft Matter
|September 7, 2019
Summary
Introducing scalar activity via temperature differences drives phase separation and crystallization in Lennard-Jones systems. Higher activity and density enhance both separation and entropy production, leading to solid-like ordered clusters.
Area of Science:
- Statistical Mechanics
- Computational Physics
- Materials Science
Background:
- Phase separation and crystallization are fundamental phenomena in condensed matter.
- Understanding how external stimuli, like activity, influence these processes is crucial.
- Lennard-Jones systems are standard models for studying fluid and solid phases.
Purpose of the Study:
- To investigate scalar activity-induced phase separation and crystallization.
- To quantify the relationship between activity, density, and thermodynamic properties.
- To analyze the structural ordering within separated phases.
Main Methods:
- Molecular Dynamics (MD) simulations of 3-dimensional Lennard-Jones particles.
- Introduction of scalar activity by creating 'hot' and 'cold' particle subsystems.
- Quantification using order parameters, entropy production calculations (2PT model, MBWR equation of state), and cluster analysis.
Main Results:
- Phase separation observed at sufficient activity ratios, increasing with density.
- Entropy production also increases with system density.
- Cluster analysis revealed solid-like ordering (FCC and HCP packing) in the largest clusters, confirmed by common neighbor analysis.
Conclusions:
- Scalar activity is a viable mechanism to induce phase separation and crystallization.
- System density plays a significant role in enhancing both phase separation and entropy production.
- The study demonstrates the formation of ordered, crystalline structures within active systems.
Related Concept Videos
02:31Phase Transitions
22.6K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
22.6K
02:39Phase Transitions: Melting and Freezing
14.6K
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...
14.6K
02:33Phase Transitions: Sublimation and Deposition
19.7K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
19.7K
02:39Phase Transitions: Vaporization and Condensation
20.7K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...
20.7K
09:32Solid-Liquid Extraction
244.3K
Source: Laboratory of Dr. Jay Deiner — City University of New York
Extraction is a crucial step in most chemical analyses. It entails removing the analyte from its sample matrix and passing it into the phase required for spectroscopic or chromatographic identification and quantification. When the sample is a solid and the required phase for analysis is a liquid, the process is called solid-liquid extraction. A simple and broadly applicable form of solid-liquid extraction entails combining...
Extraction is a crucial step in most chemical analyses. It entails removing the analyte from its sample matrix and passing it into the phase required for spectroscopic or chromatographic identification and quantification. When the sample is a solid and the required phase for analysis is a liquid, the process is called solid-liquid extraction. A simple and broadly applicable form of solid-liquid extraction entails combining...
244.3K
09:42Solid Phase Synthesis
43.3K
Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA
Merrifield's solid-phase synthesis is a Nobel Prize winning invention where a reactant molecule is bound on a solid support and undergoes successive chemical reactions to form a desired compound. When the molecules are bound to a solid support, excess reagents and byproducts can be removed by washing away the impurities, while the target compound remains bound to the resin. Specifically, we will...
Merrifield's solid-phase synthesis is a Nobel Prize winning invention where a reactant molecule is bound on a solid support and undergoes successive chemical reactions to form a desired compound. When the molecules are bound to a solid support, excess reagents and byproducts can be removed by washing away the impurities, while the target compound remains bound to the resin. Specifically, we will...
43.3K