Vibronic Structure\nof the UV/Visible Absorption Spectra\nof Phenol and Phenolate: A Hybrid Density Functional TheoryDoktorov’s\nQuantum Algorithm Approach

The\nDoktorov’s quantum algorithm has been enacted\nin combination\nwith time-dependent density functional theory (TD-DFT) to simulate\nthe vibronic structure of the UV/visible absorption spectra of the\nphenol and phenolate molecules. On the one hand, DFT and TD-DFT are\nemployed with classical algorithms to calculate the ground and excited-state\nelectronic structures as well as their vibrational frequencies and\nnormal modes, whereas, on the other hand, quantum algorithms are employed\nfor evaluating the vibrational transition intensities. In comparison\nto a previous study, <i>J. Phys. Chem. A</i> <b>2024</b>, 128, 4369–4377, which demonstrated Doktorov’s quantum\nalgorithm as a proof of concept to predict the vibronic structure\nof ionization spectra, it is applied here to medium-size molecules\nwith more than 30 vibrational normal modes, without accounting for\nDuschinsky rotations due to software limitations. This application\nto simulate the vibronic structures of the spectra of phenol and phenolate\nalso enables assessing the impact of the differences in vibrational\nfrequencies between the ground and excited electronic states.