At high temperatures there is a nematic phase that is transformed to a smectic A phase as the temperature is decreased. The results have been cross-checked by performing shear flow simulations. We have evaluated the Green-Kubo relations for the various viscosity coefficients. We have calculated the viscosities of a variant of the Gay-Berne fluid as a function of the temperature by performing molecular dynamics simulations. The large stability of the solid phase, particularly at low temperatures, would explain the unexpectedly small liquid range observed in the vapor- liquid region.įlow properties of liquid crystal phases of the Gay-Berne fluid It is suggested that the strong lateral attractive interactions present in the Gay-Berne model stabilizes the layers found in the solid phase.
Considering that the critical temperatures is Tc=0.473, the Gay-Berne model used in this work presents vapor- liquid separation over a rather narrow range of temperatures. We locate the vapor-isotropic liquid-solid triple point at a temperature TVIS=0.445. It seems that no thermodynamically stable smectic phase appears for the Gay-Berne model with the choice of parameters used in this work. The present results suggest that the high-density phase designated smectic B in previous simulations of the model is in fact a molecular solid and not a smectic liquid crystal. In view of this we locate the isotropic-nematic-solid triple point at TINS=0.85. For reduced temperatures below T=0.85 the sequence is from the isotropic phase directly to the solid state. At high temperatures the sequence of phases encountered on compression is isotropic to nematic, and then nematic to solid. Taking these fluid-solid equilibrium results as the starting points, the fluid-solid equilibrium curve was determined for a wide range of temperatures using Gibbs-Duhem integration.
Using the equation of state and free energies of the isotropic and nematic phases available in the existing literature the fluid-solid equilibrium was calculated for the temperatures selected. For a number of temperatures, NPT simulations were performed for the solid phase leading to the determination of the free energy of the solid at a reference density. The phase diagram of the Gay-Berne model with anisotropy parameters κ=3, κ'=5 has been evaluated by means of computer simulations. The global phase diagram of the Gay-Berne model