On the vibrations of formic acid predicted from first principles

Abstract

In this article, we review recent first principles, anharmonic studies on the molecular vibrations of gaseous formic acid in its monomer form. Transitions identified as fundamentals for both cis- and trans form reported in these studies are collected and supported by results from high-resolution experiments. Attention is given to the effect of coordinate coupling on the convergence of the computed vibrational states.

Fig. 1. Trans and cis isomer of formic acid with the potential energy displayed along τ, the out-of-plane H motion. Reprinted with permission from ref. from Elsevier, copyright 2022.

Fig. 2. Valence coordinates defined by Richter and Carbonniére and adopted in ref. , , and for the monomeric formic acid molecule. The torsional coordinates τ₁ and τ₂ (not depicted) describe the out-of-plane motions of H1 and H2, respectively. Reprinted with permission from ref. from AIP Publishing, copyright 2018.