A study of isotropic–nematic transition of quadrupolar Gay–Berne fluid using density-functional theory approach

Abstract

The effects of quadrupole moments on the isotropic–nematic (IN) phase transitions are studied using the density-functional theory (DFT) for a Gay–Berne (GB) fluid for a range of length-to-breadth parameters in the reduced temperature range . The pair-correlation functions of the isotropic phase, which enter into the DFT as input parameters are found by solving the Percus–Yevick integral equation theory. The method used involves an expansion of angle-dependent functions appearing in the integral equations in terms of spherical harmonics and the harmonic coefficients are obtained by an iterative algorithm. All the terms of harmonic coefficients which involve l indices up to less than or equal to 6 are considered. The numerical accuracy of the results depends on the number of spherical harmonic coefficients considered for each orientation-dependent function. As the length-to-breadth ratio of quadrupolar GB molecules is increased, the IN transition is seen to move to lower density (and pressure) at a given temperature. It has been observed that the DFT is good to study the IN transitions in such fluids. The theoretical results have also been compared with the computer simulation results wherever they are available.

Keywords:

• Gay–Berne potential
• integral equation theory
• density-functional theory
• isotropic–nematic transition

Acknowledgements

The authors are grateful to Y. Singh for his many helpful suggestions during the progress of this study. The Department of Science & Technology, India supported the work through a project grant.