Structural and spectroscopic characterization of various isotopologues of 2-hydroxyacetonitrile using highly correlated ab initio methods*
1 Departamento de Química y Física Teóricas, Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid, Spain
2 E.T.S. de Ingeniería Civil, Universidad Politécnica de Madrid, Alfonso XII, 3-5, 28014 Madrid, Spain
Received: 30 November 2016
Received in final form: 3 February 2017
Published online: 20 June 2017
Various isotopologues of 2-hydroxyacetonitrile (OHCH2CN), a detectable astrophysical molecule, are characterized using explicitly correlated coupled cluster theory (CCSD(T)-F12/AVTZ-F12). Rovibrational parameters and far infrared transitions are computed to help the interpretation of the rotational spectra and radioastronomical observations. OHCH2CN displays non-rigid properties. The OH internal rotation intertransforms two conformers, gauche and trans, whose energy separation reaches 1.41 kcal/mol. The process is restricted by energy barriers of Vt = ~ 645 cm-1 and Vg → g = ~ 425 cm-1. Isotopic effects on the rotational constants and on the torsional energy levels are evaluated for isotopic varieties containing the most abundant cosmological isotopes (13C, 18C, 15N and D). Effects are relevant for ODCH2CN where the ground vibrational state splits in two components separated by 0.51 cm-1. This gap has been evaluated to be 3.20 cm-1 for the main isotopologue.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2017