Phase transitions of hard ellipses and hard ellipses with circular square-wells based upon density functional theory

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Two versions of the decoupling approximation (DA) are used to study the isotropic-nematic phase transition of hard ellipse systems. The results of the scaling procedure with respect to hard discs and the scaling with respect to the isotropic phase of hard ellipses are compared with the corresponding Monte Carlo simulation data. In spite of the fact that, in comparison with other theories, the DA yields the best critical densities for the isotropic-nematic phase transition of hard convex bodies with respect to other theories, it is unable to predict correctly the order of orientational phase transitions in the narrow range of aspect ratio k = 4. Via the hard ellipse with circular square-wells model system the effect of the attractive forces on the isotropic-nematic phase transition is studied also. The role of these attractive forces is studied on the basis of a simple perturbation theoretical method. It is shown that at low temperatures attraction causes first-order isotropic-nematic phase separation for the values of aspect ratio studied and moreover both stable and metastable vapour-liquid coexistence can be found.

Original languageEnglish
Pages (from-to)515-523
Number of pages9
JournalMolecular Physics
Volume95
Issue number3
Publication statusPublished - Oct 20 1998

Fingerprint

square wells
Phase Transition
ellipses
Density functional theory
Phase transitions
density functional theory
decoupling
aspect ratio
Aspect ratio
scaling
Hard disk storage
data simulation
approximation
Phase separation
attraction
Vapors
vapors
perturbation
Temperature
causes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

@article{fe04aebee228438b9e5e756ca7c519fd,
title = "Phase transitions of hard ellipses and hard ellipses with circular square-wells based upon density functional theory",
abstract = "Two versions of the decoupling approximation (DA) are used to study the isotropic-nematic phase transition of hard ellipse systems. The results of the scaling procedure with respect to hard discs and the scaling with respect to the isotropic phase of hard ellipses are compared with the corresponding Monte Carlo simulation data. In spite of the fact that, in comparison with other theories, the DA yields the best critical densities for the isotropic-nematic phase transition of hard convex bodies with respect to other theories, it is unable to predict correctly the order of orientational phase transitions in the narrow range of aspect ratio k = 4. Via the hard ellipse with circular square-wells model system the effect of the attractive forces on the isotropic-nematic phase transition is studied also. The role of these attractive forces is studied on the basis of a simple perturbation theoretical method. It is shown that at low temperatures attraction causes first-order isotropic-nematic phase separation for the values of aspect ratio studied and moreover both stable and metastable vapour-liquid coexistence can be found.",
author = "S. Varga and I. Szalai",
year = "1998",
month = "10",
day = "20",
language = "English",
volume = "95",
pages = "515--523",
journal = "Molecular Physics",
issn = "0026-8976",
publisher = "Taylor and Francis Ltd.",
number = "3",

}

TY - JOUR

T1 - Phase transitions of hard ellipses and hard ellipses with circular square-wells based upon density functional theory

AU - Varga, S.

AU - Szalai, I.

PY - 1998/10/20

Y1 - 1998/10/20

N2 - Two versions of the decoupling approximation (DA) are used to study the isotropic-nematic phase transition of hard ellipse systems. The results of the scaling procedure with respect to hard discs and the scaling with respect to the isotropic phase of hard ellipses are compared with the corresponding Monte Carlo simulation data. In spite of the fact that, in comparison with other theories, the DA yields the best critical densities for the isotropic-nematic phase transition of hard convex bodies with respect to other theories, it is unable to predict correctly the order of orientational phase transitions in the narrow range of aspect ratio k = 4. Via the hard ellipse with circular square-wells model system the effect of the attractive forces on the isotropic-nematic phase transition is studied also. The role of these attractive forces is studied on the basis of a simple perturbation theoretical method. It is shown that at low temperatures attraction causes first-order isotropic-nematic phase separation for the values of aspect ratio studied and moreover both stable and metastable vapour-liquid coexistence can be found.

AB - Two versions of the decoupling approximation (DA) are used to study the isotropic-nematic phase transition of hard ellipse systems. The results of the scaling procedure with respect to hard discs and the scaling with respect to the isotropic phase of hard ellipses are compared with the corresponding Monte Carlo simulation data. In spite of the fact that, in comparison with other theories, the DA yields the best critical densities for the isotropic-nematic phase transition of hard convex bodies with respect to other theories, it is unable to predict correctly the order of orientational phase transitions in the narrow range of aspect ratio k = 4. Via the hard ellipse with circular square-wells model system the effect of the attractive forces on the isotropic-nematic phase transition is studied also. The role of these attractive forces is studied on the basis of a simple perturbation theoretical method. It is shown that at low temperatures attraction causes first-order isotropic-nematic phase separation for the values of aspect ratio studied and moreover both stable and metastable vapour-liquid coexistence can be found.

UR - http://www.scopus.com/inward/record.url?scp=0040968673&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0040968673&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0040968673

VL - 95

SP - 515

EP - 523

JO - Molecular Physics

JF - Molecular Physics

SN - 0026-8976

IS - 3

ER -