The vibronic absorption spectrum of Toluidine blue O (TBO) dye in an
aqueous solution was calculated using the time-dependent density
functional theory (TD-DFT). The calculations were performed using all
hybrid functionals supported by Gaussian16 software and 6-31++G(d,p)
basis set with IEFPCM and SMD solvent models. The IEFPCM gave
underestimated values of λmax in comparison with the experiment, what is
a manifestation of the TD-DFT “cyanine failure”. However, the SMD made
it possible to obtain good agreement between calculated and experimental
spectra. The best fit was achieved using the X3LYP functional. The
dipole moments and atomic charges of the ground and excited states of
the TBO molecule were calculated. Photoexcitation leads to an increase
in the dipole moment of the dye molecule. An insignificant photoinduced
electron transfer was found in the central ring of the chromophore of
the TBO molecule. Vibronic transitions play a significant role in the
absorption spectrum of the dye.
We introduce a quantum algorithm for simulating molecular vibrational excitations during vibronic transitions. The algorithm is used to simulate vibrational excitations of pyrrole and butane during photochemical and mechanochemical excitations.
Erbium-doped tellurite glass containing copper nanoparticles showed multi-band emission of one particular transition (4I9/2 →4I15/2, at 980 nm) due to electron-lattice coupling.
TD-DFT/DFT study of Toluidine blue O in aqueous solution: vibronic transitions and electronic properties