Fig. 3. Top, Left: CD spectrum (eqn (1)) of a twisted biphenyl calculated using the non-local formalism, eqn (1)–(13). Rotational averaging has been carried out by rotating the incoming beam on a single molecule. Top, right: chiral signal obtained by the superposition of two CPL of slightly different amplitude, eqn (17). Bottom row: same as top but for hexahelicene.