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Rotational and Torsional Properties of Various Monosubstituted Isotopologues of Acetone (CH3–CO–CH3) from Explicitly Correlated Ab Initio Methods

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journal contribution
posted on 18.03.2021, 18:09 by Samira Dalbouha, Muneerah Mogren Al-Mogren, María Luisa Senent
Geometric and spectroscopic parameters are determined using explicitly correlated coupled cluster ab initio calculations (CCSD­(T)-F12) for five monosubstituted isotopologues of acetone containing 18O, 13C, and D. The far-infrared region is explored with a variational procedure of reduced dimensionality that takes the interconversion of the nine minima of the potential energy surface into consideration. The methyl torsional barrier of the main isotopologue, computed to be 245.7 cm–1, varies slightly with the isotopic substitution. In the monodeuterated species, the two inequivalent internal rotors are hindered by two inequivalent barriers of 244.0 and 244.7 cm–1. The torsional fundamentals of the main variety are localized at 78.636 cm–112) and 128.904 cm–117). The differences between splitting components are lower than 0.02 and 0.2 cm–1 in the main isotopologue and in the isotopologues containing 18O and 13C, respectively. In the monodeuterated species the subcomponents are separated by ∼15 cm–1.