Q: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Hunter-Saxton partial differential equation can be used to describe some of the properties of these materials, and a key property of them may be described by a weighted average of the second Legendre polynomial over their distribution, which is called the Zwetkoff parameter. These materials may be modeled with the Meyer-Lubensky model or the McMillan model, which contains two order parameters. The Frank free energy gives their energy in terms of their splay, twist, and bend, and they may be described by a mean-field theory named after Maier and Saupe, or by a hard-rod model developed by Onsager. Some of them exhibit a chiral phase called cholesteric, while ones with molecules oriented into layers are known as smectic, and those that have molecules with well-ordered orientations are called the nematic type. For 10 points, name these materials commonly used in displays.
A:
Science