Abstract: We simulated the dynamical mechanism of excited states of water complexes 7-hydroxyflavone-(H₂O)₄ (7HF-(H₂O)₄) at the basis set level of TZVP, by means of B3LYP methods of density functional theory and timedependent density functional theory. The results show that intramolecular charge transfer process of the 7HF appears in the frontier molecular orbits of the first electron excited state. The molecular structure of the 7HF is reversed in the ground state and the first electron excited state. Five intermolecular hydrogen bonds in the complex appears to be a strengthening mechanism in the first electron excited state, which can drive the multiple proton transfer reaction of the excited state.

Key words: excited state, proton transfer, hydrogen bond, twisted intramolecular charge transfer