The honoree of this symposium has had a tremendous impact in many areas of chemistry, and his work at the interface between experimental and computational spectroscopy is just one example. This presentation will provide and overview of the systematic examination of the vibrational frequencies for a series of simple hydrogen bonded dimers with convergent ab initio quantum mechanical electronic structure techniques. Anharmonic effects are assessed with second-order vibrational perturbation theory (VPT2) for these homo- and heterogeneous dimers composed of small fragments such as H2O, HF, HCN, HCl, and H2S, but we are also in the process of extending the analysis to vibrational configuration interaction (VCI) theory in some cases. Direct comparison to experimentally measured fundamental vibrational frequencies reveals that VPT2 anharmonic frequencies computed with the CCSD(T) method and large correlation consistent basis sets appropriately augmented with diffuse functions typically differ by no more than a few wavenumbers for the intramonomer fundamental vibrations, including the challenging donor stretch. The corresponding dissociation energies that include the VPT2 anharmonic zero-point vibrational energies also tend to closely match reliable experimental D0 values. The computed results are usually accurate enough to identify and/or potentially resolve experimental discrepancies.

Assessing anharmonic effects in small hydrogen bonded systems

ACS Spring 2022

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