A theoretical study on the spectroscopy, structure, and stability of C2H3NS molecules

Autor: Robert Kołos, Michał Turowski, Thomas Custer, Marcin Gronowski
Rok vydání: 2016
Předmět:
Zdroj: Theoretical Chemistry Accounts. 135
ISSN: 1432-2234
1432-881X
DOI: 10.1007/s00214-016-1978-6
Popis: Here we report the results of a theoretical study devoted to the family of methyl thiocyanate (CH3–SCN) isomers. From among 14 species sharing the C2H3NS stoichiometry, the most thermodynamically stable of these are methyl isothiocyanate (CH3–NCS), methyl thiocyanate (CH3–SCN), and mercaptoacetonitrile (HS–CH2–CN). Energies were reliably predicted using the CCSD(T) variant of coupled-cluster calculations making use of a quadruple zeta-quality basis set. Minor contributions to the total energy, including scalar relativistic effects and extrapolation to the complete basis set limit, were obtained using second-order many-body perturbation theory. The three most stable isomers feature similar energy values (differing by few kJ/mol) that are much lower than those of the remaining C2H3NS species (more than 85 kJ/mol). Spectroscopic properties including rotational constants, anharmonic vibrational frequencies, infrared absorption intensities (harmonic), Raman activities, and the energies of excited electronic states have been derived using coupled-cluster or density functional theory for the whole set of C2H3NS molecules. Additionally, infrared absorption intensities and frequencies of overtone and combination bands are given for the three lowest energy isomers.
Databáze: OpenAIRE
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