Related Experiment Video
Updated: Aug 13, 2025
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
8.6K
Understanding dynamics in coarse-grained models. I. Universal excess entropy scaling relationship
Jaehyeok Jin1, Kenneth S Schweizer2, Gregory A Voth1
1Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
The Journal of Chemical Physics
|January 21, 2023
Summary
Coarse-grained (CG) models maintain universal dynamic scaling relationships with fine-grained (FG) models. Understanding mapping entropy reveals why CG models exhibit accelerated dynamics.
Area of Science:
- Computational chemistry
- Molecular dynamics
- Statistical mechanics
Background:
- Coarse-grained (CG) models simplify complex systems by reducing degrees of freedom, enabling efficient structural sampling.
- Assessing dynamic properties in CG models is challenging due to accelerated dynamics compared to fine-grained (FG) systems.
Purpose of the Study:
- To establish a better correspondence between FG and CG model dynamics.
- To investigate the applicability of excess entropy scaling to compare FG and CG dynamics.
Main Methods:
- Utilized the excess entropy scaling relationship to assess and compare dynamical properties.
- Developed a new theory for calculating excess entropies in FG and CG systems, accounting for entropy representability.
- Applied the methodology to liquid water and methanol systems at both FG and CG resolutions.
Main Results:
- Provided evidence that FG and CG models follow the same universal excess entropy scaling relationship.
- Demonstrated that scaling exponents remain unchanged during the coarse-graining process for water and methanol.
- Showed that the scaling behavior is universal for the same underlying molecular systems.
Conclusions:
- The excess entropy scaling relationship is a valid tool for comparing FG and CG dynamics.
- Coarse-graining preserves the universal dynamic scaling behavior of molecular systems.
- The concept of mapping entropy and missing entropy is crucial for understanding accelerated CG dynamics.
Related Concept Videos
02:39Entropy
30.6K
Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...
30.6K
01:20Entropy and the Second Law of Thermodynamics
3.0K
The second law of thermodynamics can be stated quantitatively using the concept of entropy. Entropy is the measure of disorder of the system.
The relation between entropy and disorder can be illustrated with the example of the phase change of ice to water. In ice, the molecules are located at specific sites giving a solid state, whereas, in a liquid form, these molecules are much freer to move. The molecular arrangement has therefore become more randomized. Although the change in average...
The relation between entropy and disorder can be illustrated with the example of the phase change of ice to water. In ice, the molecules are located at specific sites giving a solid state, whereas, in a liquid form, these molecules are much freer to move. The molecular arrangement has therefore become more randomized. Although the change in average...
3.0K
01:10Entropy Change in Reversible Processes
2.7K
In the Carnot engine, which achieves the maximum efficiency between two reservoirs of fixed temperatures, the total change in entropy is zero. The observation can be generalized by considering any reversible cyclic process consisting of many Carnot cycles. Thus, it can be stated that the total entropy change of any ideal reversible cycle is zero.
The statement can be further generalized to prove that entropy is a state function. Take a cyclic process between any two points on a p-V diagram.
The statement can be further generalized to prove that entropy is a state function. Take a cyclic process between any two points on a p-V diagram.
2.7K
02:38Third Law of Thermodynamics
19.3K
A pure, perfectly crystalline solid possessing no kinetic energy (that is, at a temperature of absolute zero, 0 K) may be described by a single microstate, as its purity, perfect crystallinity,and complete lack of motion means there is but one possible location for each identical atom or molecule comprising the crystal (W = 1). According to the Boltzmann equation, the entropy of this system is zero.
19.3K
02:49Second Law of Thermodynamics
24.1K
In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Processes that involve an increase in entropy of the system (ΔS > 0) are very often spontaneous; however, examples to the contrary are plentiful. By expanding consideration of entropy changes to include the surroundings, a significant conclusion regarding the relation between this property and spontaneity may be reached. In thermodynamic...
24.1K
01:14The Second Law of Thermodynamics
5.4K
In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Scientists refer to the measure of randomness or disorder within a system as entropy. High entropy means high disorder and low energy. To better understand entropy, think of a student’s bedroom. If no energy or work were put into it, the room would quickly become messy. It would exist in a very disordered state, one of high entropy. Energy must be...
5.4K