Low-temperature rate constants for rotational excitation and de-excitation of C3(X1Σg+) by collisions with He (1s)

The low-temperature rotational (de-) excitation of C-3(X-1 Sigma(+)(g)) by collisions with He (S-1) is studied using an ab initio potential energy surface (PES). This PES has been calculated using the single-and double-excitation coupled-cluster approach with noniterative perturbational treatment of triple excitations [CCSD(T)] and the augmented correlation-consistent triple-zeta basis set (aug-cc-pVTZ) with bond functions. This PES is then incorporated in full close-coupling quantum scattering calculations for collision energies between 0.1 and 50 cm(-1) in order to deduce the rate constants for rotational levels of C-3 up to j = 10, covering the temperature range 5-15 K.