Plyler Prize: Deciphering spectral signatures of proton delocalization in complexes of hydroxide and hydronium ions with water molecules

In this talk, we will explore the use of a variety of theoretical and computational approaches for exploring proton delocalization in complexes of hydroxide and hydronium ions with several water molecules. Over the years, the combination of theoretical work and experimental studies of these complexes have provided important insights into proton mobility in the bulk. The advantage of focusing on the smaller systems is that they allow direct comparisons to be made between experiment and calculation. In addition to providing assignments to peaks in the spectra, work on these systems provides insights into the underlying ionic hydrogen bonds. In these systems the cooperative nature of the hydrogen bond that are formed leads to large changes in the strengths of the ion-water interactions as more water molecules are introduced, and this, in turn, has a large effect on the spectroscopy.



This talk will focus on work in our group exploring the most fundamental ion-water complexes, those between water molecules and hydronium or hydroxide ions. This work employs an array of theoretical and computational approaches, ranging from analysis of the couplings of the vibrations at the harmonic level through analysis of the wave functions using diffusion Monte Carlo approaches. The work is motivated by the studies of the vibrational spectra of complexes of hydronium and hydroxide ions with up to five water molecules, performed by Mark Johnson, Knut Asmis and Michael Duncan and their groups. Recent work in the development of potential surfaces for hydroxide-water complexes will also be discussed.