Cross-sections and rate coefficients calculations for rotational excitation of cyanoethynylide ions () induced by collision with He atoms at low temperature

Abstract

The focal points of the present paper are the calculations of cross-sections and rate coefficients for rotational (de-)excitation of C3N− induced by collision with He and H2 atoms for energies of up to 2000 cm−1 and temperatures ranging from 1 K to 300 K. For this study, the new two-dimensional potential energy surface (PES) of the C3N−−He complex has been calculated at the ab initio restricted coupled cluster level of theory, including single, double and perturbative triple excitation [RCCSD(T)-F12a] with the cc-pVTZ-F12 basis set augmented by mid-bond functions. Basis set superposition errors were taken into account. To allow for the dynamical calculations, the PES was then fitted to a global analytical form, the main features of which are discussed. Collisional cross-sections among the first 17 rotational levels were calculated and employed to compute downward and upward rate coefficients. A propensity towards was observed.