Liquid Crystal (LCD) Field Dependent Capacitance

clex22.in : Liquid Crystal (LCD) Field Dependent Capacitance

Requires: CLEVER, VICTORYPROCESS

This example illustrates using Clever to simulate the physics in Liquid Crystal films. Liquid crystal films consist of long molecules, called directors which rotate in response to applied electric fields, that effectively supplies a rotational torque. The permittivity and hence the capacitance of these LCD films, is highly directional and dependent on the the orientation of the long molecules (directors). When an electric field is applied which rotates these molecules, the capacitance in the direction across the film, can change dramatically. Clever simulates this physics, in order to calculate the voltage (field) dependent capacitance of LCD layers.

The directional permittivities of the LCD versus director angle are defined in the setLC statement.

The layers which interface the LCD film can anchor the LCD molecules in a fixed direction, regardless of applied field. This creates an increasing angular rotation of the LCD molecules with applied field, the further they are away from these anchored interface regions. These physical effects are also included in the simulations. Specifying these fixed interface angles for top and bottom interfaces is executed by the statements LCbndaryT and LCbndaryB

Clearly, if an applied voltage changes the permittivity of a film, the stored charge and capacitance is also voltage dependent. Since Q=CxV, where Q is stored charge, C is layer capacitance in a particular direction and V is applied voltage, mathematical instability can result at certain applied voltages due to the inter-dependence of all three parameters. The purpose of the cPenalty parameter, is to introduce a modicum of numerical damping, to calm these numerical instabilities.

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.