jz6b02561_si_001.pdf (2.11 MB)
Download fileHow the Zundel (H5O2+) Potential Can Be Used to Predict the Proton Stretch and Bend Frequencies of Larger Protonated Water Clusters
journal contribution
posted on 2016-11-28, 00:00 authored by Qi Yu, Joel M. BowmanFrom
a series of seminal experiments on the IR spectra of protonated
water clusters and associated theoretical analyses, it is clear that
the energies and spectral features of the proton stretch and bend
modes are very sensitive functions of the cluster size. Here we show
that this dynamic range can be understood by examining the sensitivity
of these modes in the potential of the Zundel cation, H5O2+, as the
separation of the two water monomers is varied. As this distance increases,
the proton increasingly localizes on a monomer, and this is encoded
in the IR spectrum of the proton vibrational modes. The quantitative
predictions from this simple correlation are verified for the H7O3+ and
H9O4+ clusters, for which new benchmark harmonic frequencies are reported.
The predictions are also in good accord with trends seen experimentally
and previous calculations for these and five other clusters, including
H+(H2O)21.