Orientational Phase Transition of Long Elongated Gay–Berne Molecules

Abstract

We have performed a detailed study of the temperature dependence and of the isotropic–nematic phase transition in a fluid of moderately long elongated molecules interacting via a Gay–Berne potential with anisotropy parameters x ₀ = 4.4, k′ = 20.0, μ = 1, andν = 1. The nematic phase is found to be stable with respect to the isotropic phase for reduced temperatures T* ≤ 1.60. In the temperature range 1.60 ≤ T* ≤ 3.0, the phase boundaries of the isotropic–nematic transition are obtained by using the density-functional theory. The pair-correlation functions of the isotropic phase that enter in the density-functional theory as input informations are found from the Percus–Yevick integral equation theory. The accuracy of the Percus–Yevick integral equation theory has been tested by comparing the pair-correlation functions of the Gay–Berne fluids with computer simulation results. The density-functional theory is good enough to study the freezing parameters of complex fluids if the values of the pair-correlation functions of the isotropic phase are known accurately.

Keywords:

• density-functional theory
• Gay–Berne potential
• isotropic–nematic transition
• pair-correlation functions

ACKNOWLEDGMENTS

We are very grateful to G. R. Luckhurst and M. A. Bates for providing the computer simulation data for comparison. The work was supported by the Department of Science and Technology, India, through a project grant. We thank the principal and management of the college for providing the necessary facilities.