Full-dimensional quantum dynamics of rovibrationally inelastic scattering between CN and H₂

We report six-dimensional (6D) potential energy surface (PES) and rovibrational scattering calculations for the CN-H₂ collision system. The PES was computed using the high-level ab initio spin-restricted coupled-cluster with single, double, and perturbative triple excitations-F12B method and fitted to an analytic function using an invariant polynomial method in 6D. Quantum close-coupling calculations are reported for rotational transitions in CN by H₂ and D₂ collisions in 6D as well as four-dimensional (4D) within a rigid rotor model for collision energies of 1.0-1500 cm⁻¹. Comparisons with experimental data and previous 4D calculations are presented for CN rotational levels j₁ = 4 and 11. For the first time, rovibrational quenching cross sections and rate coefficients of CN (v₁ = 1,j₁ = 0) in collisions with para- and ortho-H₂ are also reported in full-dimension. Agreement for pure rotational transitions is found to be good, but no experimental data on rovibrational collisional quenching for CN-H₂ are available. Applications of the current rotational and rovibrational rate coefficients in astrophysical modeling are briefly discussed.