Environmental effects on electronic absorption spectra using DFT: An organicand positively charged fused polycyclic chromophore as a case study

摘要

The benzo[1,2]quinolizino[3,4,5,6-deflphenanthridinium,-9-phenyl molecule (hereafter BQPT-ph+) hasbeen considered as a representative benchmark for simple organic and positively charged systems insolution to test the environmental effects on computed UV-Visible spectra. In particular the effects, bothat geometric and electronic levels, related to the inclusion of bulk solvent, using a polarizable continuummodel (PCM), and the explicit inclusion of the counterion (here BF4-) will be discussed. Electronic tran-sitions were computed at TD-DFT level using a hybrid exchange correlation functional (PBEO) and a dou-ble zeta valence basis set. Effect of inclusion of diffuse and polarization function on the computedelectronic spectra will also be discussed. Finally, the importance of the vibronic structure to simulate the experimental band shape will be con-sidered focusing on the first electronic transition, and computing ground and first excited states opti-mized structures together with harmonic frequencies at DFT and TD-DFT level, respectively. The goodagreement obtained between computed and experimental spectra confirms the good quality of boththe optimized geometries and the harmonic force fields.