For chiral oligomers, we assume that, except for the PDIs located in two sides of the oligomer chain, each PDI in the middle of the oligomer chain has a transition electronic dipole of the same magnitude but oriented differently in space. The magnitude and direction of the transition magnetic dipole for each PDI are related to its relative spatial position. Typically, we ignore the intrinsic transition magnetic dipole of each molecular unit. The relationship between the transition magnetic dipole and electronic dipole can be obtained from