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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Thermodynamic description of liquid-state limits.
1Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom. les.woodcock@manchester.ac.uk
The Journal of Physical Chemistry. B
|March 20, 2012
Summary
Random close packing (RCP) of spheres achieves a thermodynamic ground state, crucial for liquid equilibria. This state, with a packing fraction of 0.6366, is comparable to dense hard-sphere fluids.
Area of Science:
- Physics
- Thermodynamics
- Statistical Mechanics
Background:
- The thermodynamic status of random close packing (RCP) is fundamental for understanding liquid-state equilibria.
- Existing models like the Mayer virial expansion fail to accurately describe dense fluid equations of state beyond the available-volume percolation transition.
Purpose of the Study:
- To establish the thermodynamic status of the random close packing (RCP) state.
- To investigate the role of RCP in liquid-state equilibria and its relationship with percolation transitions.
- To explore liquid-vapor coexistence properties for square-well (SW) attractive spheres.
Main Methods:
- Monte Carlo (MC) simulations were employed to calculate liquid-state coexistence properties of square-well (SW) attractive spheres.
- Analysis of existing MC results for liquid-vapor coexistence in SW fluids.
- Examination of percolation transitions in hard-sphere and SW fluids.
Main Results:
- The limiting packing fraction for RCP was determined as 0.6366 ± 0.0005, with residual entropy approximately equal to Boltzmann's constant.
- A RCP state is inferred to belong to the same thermodynamic phase as pre-percolation equilibrium dense hard-sphere fluids.
- The available-volume percolation transition is strengthened by SW perturbation and becomes first order at the critical temperature, leading to liquid-vapor coexistence.
Conclusions:
- The RCP state possesses a defined thermodynamic status and plays a critical role in liquid equilibria.
- The thermodynamic description of coexistence limits for SW fluids is applicable to real liquids, exemplified by liquid argon.
- Percolation transitions significantly influence liquid-vapor coexistence in dense fluids.
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