CHIRALITY MEASURE AND CHIRAL ORDER-PARAMETER FOR A 2-DIMENSIONAL SYSTEM

A chirality measure and a chiral order parameter are defined for two-d imensional systems based upon the transformation properties of pseudot ensors. The quantities are derived by considering the polarization ind uced by an electric field applied normal to a system comprising a vacu um above an inhomogeneous dielectric bounded by a plane surface. The q uantities are defined by analogy to the three-dimensional case which h as been considered by the authors previously. The index is illustrated by a calculation of the chiral order parameter for an Archimedean spi ral structure.