Shortcomings of the Q Tensor Method for Modeling Liquid Crystal Devices

Because writing the free energy in terms of the order parameter tensor, Q, maintains the equivalence of n and −n, while writing it in terms of the director, n does not, it has been thought that the tensor approach was more correct. We found that this equivalence can cause a simulation to transform between topologically inequivalent states without a wall disclination, a non-physical situtation. The reasons usually given for using the tensor method thus must be flawed when simulating devices. Because the vector approach is also mathematically simpler, computationally faster and requires fewer grid points, it is the suggested simulation method.