New de-excitation rates of the open shell dicarbon monoxide C2O(X3 Σ−) in collision with He(1S).

In order to derive accurate physical conditions of the interstellar clouds (such as TMC-1) from the rotational transitions of C₂O, collisional rates are needed. Based on a new two-dimensional potential energy surface (PES), we report a new rate coefficients calculation of C₂O(X ³Σ⁻) induced by collision with He. This PES was obtained from the explicitly correlated restricted open-shell coupled cluster with single, double, and perturbative triple excitation (rccsd(t)-f12) ab initio approach associated with aug-cc-pVTZ basis sets. The C₂O–He PES presents one minimum below its dissociation limit with a well depth of 42.376 cm⁻¹. The close-coupling quantum time-independent formalism was used to derive cross sections for E ≤ 370 cm⁻¹ and N ≤ 10. De-excitation rate coefficients are obtained for thermal temperature below 80 K. [ABSTRACT FROM AUTHOR]