C3 by collision with H2

An accurate analysis of the physical-chemical conditions in the regions of the interstellar medium in which C_3_ is observed requires knowing the collisional rate coefficients of this molecule with He, H_2_, electrons, and H. The main goals of this study are to present the first potential energy surface for the C_3_ +H_2_ complex, to study the dynamics of the system, and to report a set of rate coefficients at low temperature for the lower rotational states of C_3_ with para- and ortho-H_2_.

Methods. A large grid of ab initio energies was computed at the explicitly correlated coupled-cluster with single-, double-, and perturbative triple-excitation level of theory, together with the augmented correlation-consistent quadruple zeta basis set (CCSD(T)-F12a/aug-cc-pVQZ). This grid of energies was fit to an analytical function.