Monte Carlo Simulation of the Nematic-Isotropic Phase Transition of Liquid Crystals under Magnetic Field

Abstract

The effect of magnetic field on the nematic- isotropic phase transition of liquid crystal was studied by Monte Carlo simulation. The classical spin lattice model was used to describe the liquid crystal systems and the Lebwohl-Lasher potential model. We calculate the energy per spin, the orientational order parameter, and specific heat of subtances and then study their phase diagrams as a function of temperature for various magnetic fields and as a function of magnetic field for various temperatures. In the absence of magnetic field, the nematic-isotropic phase transition is a weak first order transition. If the magnetic field is increased, then the minimum value of the spin energy will drop, the minimum value of the order parameter will increase, and the peak value of the specific heat is going down. We find that the magnetic field shifts the nematic-isotropic phase transition and induces an isotropic phase into a paranematic phase.