Spectroscopy and physics of atoms and molecules

Calculation of the structure and infrared absorption spectra of hydrogen-bonded complexes of methyl formate with water

V. P. Bulychev, M. V. Buturlimova

Saint Petersburg State University

Abstract: Equilibrium nuclear configurations of four heterodimers formed by the most stable cis conformer of a methyl formate molecule with a water molecule are calculated using the MP2/aug-cc-pVTZ method with the basis set superposition error taken into account. The geometrical parameters of the heterodimers, the binding energies, and the charges on atoms are determined. The frequencies and intensities for the IR absorption bands of heterodimers are calculated in the harmonic approximation and also in the anharmonic approximation with the use of the second-order perturbation theory. The strongest absorption bands of heterodimers that can be used to detect these complexes in an experiment were determined. The correlations were analyzed between the changes of geometrical parameters of monomers, charges on atoms, and shifts of vibrational frequencies arising upon formation of intermolecular hydrogen bonds. The calculated frequency shifts of vibrational absorption bands of monomers upon formation of heterodimers were compared with the data of a low-temperature experiment in solid neon.

Keywords: hydrogen bond, calculations of the spectra of molecular complexes, anharmonic interactions.

Received: 14.04.2025
Revised: 18.05.2025
Accepted: 08.06.2025

DOI: 10.61011/OS.2025.07.61102.7815-25

Bibliographic databases:

•