Wavepacket dynamical study of H-atom tunneling in catecholate monoanion: the role of intermode couplings and energy flow.

We present a study of H-atom tunneling in catecholate monoanion through wavepacket dynamical simulations. In our earlier study of this symmetrical double-well system [ Phys. Chem. Chem. Phys. , 2022, 24 , 10887], a limited number of transition state modes were identified as being important for the tunneling process. These include the imaginary frequency mode Q 1 , the CO scissor mode Q 10 , and the OHO bending mode Q 29 . In this work, starting from non-stationary initial states prepared with excitations in these modes, we have carried out wavepacket dynamics in two and three dimensional spaces. We analyse the dynamical effects of the intermode couplings, in particular the role of energy flow between the studied modes on H-atom tunneling. We find that while Q 10 strongly modulates the donor-acceptor distance, it does not exchange energy with Q 1 . However, excitation in Q 29 or Q 1 does lead to rapid energy exchange between these modes, which modifies the tunneling rate at early times.