## Abstract

Consider a smectic A structure in which each layer is in effect a two-dimensional fluid with its director normal to the layers. If we assume the layers to be incompressible, the integral\(
\frac{1}{a}\int_P^O {n.dr}
\) represents the number of layers crossed on going from *P* to *Q*, where *a* is the layer thickness. In a disclination-free sample this number should be independent of the path chosen so that ∇ × **n** = 0. Hence **n**. ∇ × **n** = 0 and **n** × ∇ × n = 0. In other words both twist and bend distortions are absent and only the splay term remains in the Frank free-energy expression.

## Keywords

Liquid Crystal Nematic Phase Smectic Phase Permanent Dipole Moment Smectic Layer
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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## Copyright information

© Plenum Press, New York 1984