Impact of Vibronic Couplings on Perceived Colors: Two Anthraquinones as a Working Example.

The accurate simulation of the dye colors remains a significant challenge for theoreticians, notably due to the sensitivity of the human eyes that are able to distinguish variations of hues corresponding to trifling energetic shifts. Using time-dependent density functional theory and two hybrid functionals, we have simulated vibrationally resolved absorption spectra of two anthraquinone derivatives (solvent blue 35 and solvent green 3) solvated in cyclohexane. Comparisons with recent experiments demonstrate the efficiency of the ωB97X-D/6-31++G(d,p) approach for these structures. The impact of microscopic vibronic couplings on the macroscopic chromatic coordinates of the dyes is quantified. This work unravels the key role of these couplings and is consequently a step further in the modeling of human-perceived colors from purely ab initio models.