In several gas-phase water-ion clusters, including HCO2-(H2O), NO3-(H2O), and CH3CO2-(H2O), the vibrational spectrum in the OH stretch region displays a progression of peaks with nearly even spacing. Previous theoretical studies have been able to qualitatively reproduce this progression with a simple cubic coupling between the intermolecular rock and two water OH stretch normal modes. In this work, we use the HCO2-(H2O) cluster to examine the assumptions and of this model. We also investigate the use of a one-dimensional adiabatic model based on ab initio energies and frequencies calculated as a function of the rock angle to calculate the spectra of HCO2-(H2O), as well as its isotopomers. We present the advantages and challenges for implementing an adiabatic model in this system, discussing how a variable reduced mass, anharmonic frequencies, and very accurate electronic structure methods are all required to obtain a good agreement with experimental results.

Calculation of the peak progression in the vibrational spectrum of HCO2-(H2O) in the OH stretch region: application of a one-dimensional adiabatic model

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.