UV/Vis Absorption Spectrum calculations of Benzo-1,2-dipyrene Isomer using Long-Range Corrected Density Functional Theory

Abstract Anti- and syn-isomers of benzo-1,2-dipyrene were synthesized, and nonidentical experimental absorption spectra were observed. The B3LYP, B3LYP-D3, ωB97XD, and optimally tuned long-range corrected (LC) BOP functionals were assessed. B3LYP and B3LYP-D3 underestimated and ωB97XD overestimated the fundamental gaps and their following optical gaps in both isomers. The LC-BOP functional with the range separation parameter (µ=0.18) using the geometries optimized with LCgau-BOP+LRD reproduced the experimental absorption spectra of both isomers well. Therefore, in the case of the absorption spectrum calculation of the excimer-like isomers, it is significant to include both the weak interaction term and long-range Hartree-Fock exchange interaction appropriately.