Thermodynamic stability of soft-core Lennard-Jones fluids and their mixtures

Journal: Journal of Chemical Physics

Volume: 132

Issue: 6

ISSN: 0021-9606

DOI: 10.1063/1.3319510

Abstract:

Thermodynamic stability of model single component and binary mixture fluids is considered with the Fisher-Ruelle (FR) stability criteria, which apply in the thermodynamic limit, and molecular dynamics (MD) simulation for finite periodic systems. Two soft-core potential forms are considered, φ6,1(r)=4[1/(a+r6)2-1/(a+r6)] and φ2,3(r)=4[1/(a+r2)6-1/(a+r2) 3], where r is the separation between the particle centers. According to FR these are unstable in the thermodynamic limit if a>a c=1/2 and a>ac=(7/32)1/3, respectively. MD simulations with single-component particles show, however, that this transition on typical simulation times is more gradual for finite periodic systems with variation in a on either side of ac. For aa c, with the unstable component in the mixture breaking up into many long-lived microdroplets which conferred apparent equilibrium thermodynamic behavior (i.e., negligible N -dependence of the average potential energy per particle) in this period. © 2010 American Institute of Physics.

Source: Scopus

Preferred by: David Heyes

Thermodynamic stability of soft-core Lennard-Jones fluids and their mixtures.

Authors: Heyes, D.M.

Journal: J Chem Phys

Volume: 132

Issue: 6

Pages: 064504

eISSN: 1089-7690

DOI: 10.1063/1.3319510

Abstract:

Thermodynamic stability of model single component and binary mixture fluids is considered with the Fisher-Ruelle (FR) stability criteria, which apply in the thermodynamic limit, and molecular dynamics (MD) simulation for finite periodic systems. Two soft-core potential forms are considered, phi(6,1)(r)=4[1/(a+r(6))(2)-1/(a+r(6))] and phi(2,3)(r)=4[1/(a+r(2))(6)-1/(a+r(2))(3)], where r is the separation between the particle centers. According to FR these are unstable in the thermodynamic limit if a>a(c)=1/2 and a>a(c)=(7/32)(1/3), respectively. MD simulations with single-component particles show, however, that this transition on typical simulation times is more gradual for finite periodic systems with variation in a on either side of a(c). For aa(c), with the unstable component in the mixture breaking up into many long-lived microdroplets which conferred apparent equilibrium thermodynamic behavior (i.e., negligible N-dependence of the average potential energy per particle) in this period.

Source: PubMed

Thermodynamic stability of soft-core Lennard-Jones fluids and their mixtures

Authors: Heyes, D.M.

Journal: JOURNAL OF CHEMICAL PHYSICS

Volume: 132

Issue: 6

ISSN: 0021-9606

DOI: 10.1063/1.3319510

Source: Web of Science (Lite)

Thermodynamic stability of soft-core Lennard-Jones fluids and their mixtures.

Authors: Heyes, D.M.

Journal: The Journal of chemical physics

Volume: 132

Issue: 6

Pages: 064504

eISSN: 1089-7690

ISSN: 0021-9606

DOI: 10.1063/1.3319510

Abstract:

Thermodynamic stability of model single component and binary mixture fluids is considered with the Fisher-Ruelle (FR) stability criteria, which apply in the thermodynamic limit, and molecular dynamics (MD) simulation for finite periodic systems. Two soft-core potential forms are considered, phi(6,1)(r)=4[1/(a+r(6))(2)-1/(a+r(6))] and phi(2,3)(r)=4[1/(a+r(2))(6)-1/(a+r(2))(3)], where r is the separation between the particle centers. According to FR these are unstable in the thermodynamic limit if a>a(c)=1/2 and a>a(c)=(7/32)(1/3), respectively. MD simulations with single-component particles show, however, that this transition on typical simulation times is more gradual for finite periodic systems with variation in a on either side of a(c). For aa(c), with the unstable component in the mixture breaking up into many long-lived microdroplets which conferred apparent equilibrium thermodynamic behavior (i.e., negligible N-dependence of the average potential energy per particle) in this period.

Source: Europe PubMed Central