Microscopic Origin of Cholesteric Pitch

Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104(February 1, 2008)We present a microscopic analysis of the instability of the nematic phase to chirality when molecularchirality is introduced perturbatively. We show that for central force interactions the previouslyneglected short–range biaxial correlations play a crucial role in determining the cholesteric pitch.We propose a pseudoscalar strength which quantifies the chirality of a molecule.PACS numbers: 61.30.Cz, 33.15.Bh, 05.20.-y