Fig. 4. Component M = 0 of the antisymmetric part of the response tensor (left, eqn (7)), total current density (center, eqn (6)) and integrand J·A that generates the signal (right, eqn (8)) for twisted biphenyl (top) and hexahelicene (bottom). The antisymmetric part of the response tensor is calculated for the first transition (ground state to first electronic excited state). J and J·A are calculated from eqn (6) for an A field resonant with the first transition.