Eur. Phys. J. D (2017) 71: 161
https://doi.org/10.1140/epjd/e2017-70748-y

Regular Article

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

^a e-mail; senent@iem.cfmac.csic.es

Received: 30 November 2016
Received in final form: 3 February 2017
Published online: 20 June 2017

Abstract

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 V_t = ~ 645 cm^-1 and V_{g → 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.