Symmetry Analysis
The fundamental properties of liquid crystals are governed by their symmetries, which dictate the possible order parameters and their associated transformations.
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The statement of the theorem
Let be the point group symmetry of the liquid crystal phase. The physical properties are invariant under the action of . The order parameters must transform according to the irreducible representations (irreps) of . The free energy density must be a scalar invariant under the group action: \n \nThis requires that can be expressed as a linear combination of the basis invariants of the group.