On the helical twisting power of chiral dopants in liquid crystals

The helical twisting power of chiral dimers formed from uniaxial hard ellipsoids has been calculated using a very simple approximation for the pair density. The method requires evaluating the difference in chemical potentials between the mirror image forms, in the twisted nematic phase. Comparison with simulation data shows the theory to be remarkably accurate, which is due to the fact that accurate absolute free energies are not required in the calculation. The extension of the method to chiral n-mers is indicated.