The Landau free energy of hard ellipses obtained from microscopic simulations.
Systems of two-dimensional hard ellipses of varying aspect ratios and packing fractions are studied by Monte Carlo simulations in the generalised canonical ensemble. From this microscopic model, we extract a coarse-grained macroscopic Landau-de Gennes free energy as a function of packing fraction and orientational order parameter. We separate the free energy into the ideal orientational entropy of non-interacting two-dimensional spins and an excess free energy associated with excluded volume interactions. We further explore the isotropic-nematic phase transition using our empirical expression for the free energy and find that the nature of the phase transition is continuous for the aspect ratios we studied.
ETH Zürich, Department of Materials, Polymer Physics, CH-8093 Zürich, Switzerland.
Alan M
AM
Luo
ETH Zürich, Department of Materials, Polymer Physics, CH-8093 Zürich, Switzerland.
Leonard M C
LM
Sagis
ETH Zürich, Department of Materials, Polymer Physics, CH-8093 Zürich, Switzerland.
Patrick
P
Ilg