Equilibrium and stability of liquid-crystal configurations in an electric field

We describe how to choose the most stable of several equilibrium states that may exist in a liquid-crystal cell at the same voltage V (or charge Q). Among states that exist at the same charge Q, the state with the lowest total free energy F is the most stable. Among states that exist at the same voltage V, the state with the lowest electric Gibbs function (F−QV) is the most stable. Thus the relative stability of various equilibrium states can be compared by plotting G against V or F against Q. An example is given to illustrate the importance of a correct pairing of thermodynamic functions and independent variables.