Raman and infrared spectra of dimethyl ether 13C-isotopologue (CH3O13CH3) from a CCSD(T) potential energy surface

• Published in: Journal of molecular spectroscopy 2012-09, Vol.279, p.3-11
• Main Authors: Carvajal, M., Álvarez-Bajo, O., Senent, M.L., Domínguez-Gómez, R., Villa, M.
• Format: Article
• Language: English
• Subjects: Ab initio; CH3OCH3; Dimethyl ether; Infrared; Isotopologues; Raman
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2012.07.018

[Display omitted] ► Study of low-lying vibrational bands of 13C-dimethyl ether. ► A 3D Hamiltonian involving two CH3 internal rotors and the COC-bending is solved. ► A CCSD(T) potential energy surface already reported for the main species was used. ► Transition frequencies in the infrared and Raman spectra have been predicted. ► A symmetrization procedure different to a textbook approach is carried out. So far, no experimental data of the infrared and Raman spectra of 13C isotopologue of dimethyl ether are available. With the aim of providing some clues of its low-lying vibrational bands and with the hope of contributing in a next spectral analysis, a number of vibrational transition frequencies below 300cm−1 of the infrared spectrum and around 400cm−1 of the Raman spectrum have been predicted and their assignments were proposed. Calculations were carried out through an ab initio three dimensional potential energy surface based on a previously reported one for the most abundant dimethyl ether isotopologue (M. Villa et al., J. Phys. Chem. A 115 (2011) 13573). The potential function was vibrationally corrected and computed with a highly correlated CCSD(T) method involving the COC bending angle and the two large amplitude CH3 internal rotation degrees of freedom. Also, the Hamiltonian parameters could represent a support for the spectral characterization of this species. Although the computed vibrational term values are expected to be very accurate, an empirical adjustment of the Hamiltonian has been performed with the purpose of anticipating some workable corrections to any possible divergence of the vibrational frequencies. Also, the symmetry breaking derived from the isotopic substitution of 13C in the dimethyl ether was taken into account when the symmetrization procedure was applied.