Wydział Chemii

Anatoly M. Yaremko

Henryk Ratajczak

Austin J. Barnes

Jan Baran

Piotr Durlak

Zdzisław Latajka

2009

Chemical Physics

364

51-63

10.1016/j.chemphys.2009.08.011

Naukowa

Angielski

Artykuł

The vibrational spectra of polycrystalline benzoic acid (BA) and its deuterated derivative were studied over the wide frequency region 4000–10 cm⁻¹ by IR and Raman methods. A theoretical analysis of the hydrogen bond frequency region and calculations at the B3LYP/6-311++G(2d, 2p) level for the benzoic acid cyclic dimer in the gas phase were made. In order to study the dynamics of proton transfer two formalisms were applied: Car–Parrinello Molecular Dynamics (CPMD) and Path Integrals Molecular Dynamics (PIMD). It was shown that the experimentally observed very broad ν-OH band absorption is the result of complex anharmonic interaction: Fermi resonance between the OH-stretching and bending vibrations and strong interaction of the ν-OH stretching with the low frequency phonons. The theoretical analysis in the framework of such an approach gave a good correlation with experiment. From the CPMD calculations it was confirmed that the O–H⋯O bridge is not rigid, with the O⋯O distance being described by a large amplitude motion. For the benzoic acid dimer we observed stepwise (asynchronous) proton transfer.

Infrared spectra, Hydrogen bond, Fermi resonance, Anharmonic interaction, Proton transfer

https://doi.org/10.1016/j.chemphys.2009.08.011

http://www.elsevier.com