A Dissipative Particle Dynamics Study of Liquid Crystals Under Electric Field

We study the equilibrium and dynamic behavior of liquid crystals (LCs) under dc and ac electric field using a mesoscopic simulation technique, Dissipative Particle Dynamics (DPD). We quantify the reorientation of LC molecules and the change in their anisotropic character under external perturbation by an order parameter. We find that the electric field magnitude has to be above a critical value to initiate the reorientation of the director of the LC system along the applied electric field, which is consistent with the experimental observations. The response time of the reorientation process decreases as the magnitude of the electric increases for the dc fields. The effect of ac field frequency on the order parameter is correlated with the field amplitude. The cyclic variation in the order parameter follows the ac field when the oscillation period is greater than the response time of the system and the amplitude is greater than the critical value. Results suggest that the DPD technique can provide important insights in to the dynamic behavior of LC system under both dc and ac electric fields. This technique can further be applied to examine the properties of colloidal LCs which can be very useful for many practical applications.