The protonated water trimer and its giant Fermi resonances

PyVisA: Visualization and Analysis of path sampling trajectories

“…It should be noted that our work does not aim to improve the current physical understanding of the reaction but instead has chiefly a modeling integration objective. Our results integrates the findings of the work of Geissler et al 22 For an improved physical description of the proton transfer mechanisms, path sampling shall be used with more recent models such as improved SD, 23 density functional theory, 24 Møller‐Plesset perturbation theory, 25 vibrational motion 26,27 and finally, the Neural Network Potentials at Coupled Cluster Accuracy 28 …”

“…This has been claimed to generate large deviations in the rate computation when considering reduced dimensionality approaches 46 . This vibration can be mapped, as an independent degree of freedom, in the initial and final stable states, as well as during the reaction since it can induce a Fermi resonance 26,27 that might significantly alter the reaction dynamic. To assert if the hydrogen distances correlate with the reaction, classifiers can be employed.…”

Using Diffusion Monte Carlo Wave Functions to Analyze the Vibrational Spectra of H7O3+ and H9O4+

“…Experimental and theoretical studies of H + (H 2 O) n =1–4 have demonstrated that the incorporation of nuclear quantum effects is essential to obtain an accurate description of the vibrational dynamics and spectroscopy of these systems. ,− Additionally, these studies show how the position, width and structure of the spectral feature that corresponds to the transition to the state with one quantum of excitation in a hydrogen-bonded OH stretch in the hydronium core is modulated by the cluster size and solvation environment . Much can be learned from the analysis and theoretical reproduction of the spectra of the protonated water clusters.…”

“…These couplings are also responsible for the evolution of the spectral envelope of the feature associated with the shared proton stretch. These large couplings make protonated water clusters challenging systems for computational approaches, such as vibrational perturbation theory (VPT2) or reduced dimensional treatments, which rely on a good zero-order description. ,,, An alternative approach involves the use of large basis set calculations, e.g. vibrational self-consistent field/vibrational configuration interaction (VSCF/VCI) approaches.…”

“…Previous theoretical studies of H 7 O 3 + have shown that the series of intense peaks in the region of the Δ n = 1 transition of the shared proton stretch result from intensity borrowing. ,,,, Specifically, there are a number of vibrational states that are nearly degenerate with the state with one quantum of excitation in the shared proton stretching mode, which can mix with that state. The importance of intensity borrowing among several states makes the interpretation of this region of the spectrum difficult.…”