We present the theoretical study of the Vibrationally Resolved Absorption (ABS), Electronic Circular Dichroism (ECD), Emission and Circularly Polarized Luminescence (CPL) spectra of a boron-fused double helicene with a detailed and complete discussion of the alternative possible approximate methods. Our results show that both Adiabatic Hessian (AH) and Vertical Hessian (VH) models have well reproduced the experimental vibronic structures and VH model shows a better performance in the simulation of spectral line-shapes. They also show that HT effect dominates the shapes of EMI and CPL, tuning the relative heights of the different vibronic peaks. Improving the agreement with the experiment for EMI. Moreover, Herzberg-Teller (HT) effect is the main reason for the mirror-symmetry breaking between ECD and CPL spectra.
