Further analysis of the dynamically averaged vibrational spectrum for the “magic” protonated 21-water cluster

A temperature dependent analysis of the vibrational spectrum of the protonated 21-water cluster is provided using the ab initio molecular dynamics method called atom-centered density matrix propagation. It is found that even at low temperatures, finite temperature dynamical averaging greatly influences the spectral results. While the current publication deals with an analysis of the vibrational spectrum at many internal temperatures, the general conclusions are consistent with those in an earlier publication [Iyengar et al., J. Chem. Phys.123, 084309 (2005)]. Furthermore, a critical spectral region (below 1500cm−1) is found for this system, where the key vibrations of the protonated species can be detected.