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Nematic phases in fluids of biaxial particles

University of British Columbia

The investigation of the possible uniaxial phases of a fluid of biaxial particles undertaken by Bergersen, Palffy-Muhoray and Dunmur forms the starting point for further research into the full range of possible phases of such a fluid. A generalization of their interaction model, free from constraints having to do with interaction details, retaining only the biaxial symmetry, is used in the mean-field approximation to explore the range of possible orientationally-ordered phases for such a system. This model is an equilibrium model which does not include dynamic effects. The basic inter-particle interaction is abstract, having the correct symmetry for biaxial particles, and is the most general biaxial interaction constructable from lowest-order scalar invariants. The self-consistent equations resulting from this formulation are obtained in the mean-field approximation and therefore retain both the symmetry and the generality at the cost of exact numerical correctness. Four order parameters are identified, corresponding (within a numerical factor) to those found by Straley and Freiser, as well as those of Bergersen et al. The phase diagram of a fluid of biaxial particles, then, is mapped out in terms of the behavior of these order parameters, as indicated by the self-consistent equations, as a function of three anisotropy parameters and the temperature. The primary method of analysis is iteration of the self-consistent equations obtained from differentiating the free energy. Numerical results are obtained for the location of the phase boundaries, and the temperature dependence of the order parameters in various phases.

Text

2010-08-22

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http://hdl.handle.net/2429/27625

Physics

University of British Columbia

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