Theoretical modeling of vibrational spectra and multidimensional proton tunneling in hydrogen-bonded systems

Multidimensional proton tunneling in symmetric hydrogen-bonded systems is described by multidimensional model potentials. The potentials have been fitted to the calculated energy barrier, normal modes and frequencies, and used to analyze proton dynamics. The model PES predicts monotonic increase of the tunneling splitting with the excitation of the planar modes. Depending of the sign of the coupling parameter out-of-plane modes can either suppress or promote the tunneling. Results of theoretical studies are presented for several systems.