The preferred alignment direction (the director) may be twisted by the application of external forces. This gives a structure rather like a spiral staircase, illustrated in this sketch of a twisted nematic phase. The selected layers are purely for illustration.
The liquid crystal naturally resists the imposition of this twist, like a spring: it costs energy to wind it up. The strength of this resistance is measured by one of the Frank elastic constants; these quantities are of interest in the design of display devices. We have developed new techniques to measure these quantities in simulations.