Full-Dimensional Quantum Dynamics of SiO in Collision with H₂

We report the first full-dimensional potential energy surface (PES) and quantum mechanical close-coupling calculations for scattering of SiO due to H₂. The full-dimensional interaction potential surface was computed using the explicitly correlated coupled-cluster (CCSD(T)-F12b) method and fitted using an invariant polynomial approach. Pure rotational quenching cross sections from initial states v₁ = 0, j₁ = 1-5 of SiO in collision with H₂ are calculated for collision energies between 1.0 and 5000 cm^-1. State-to-state rotational rate coefficients are calculated at temperatures between 5 and 1000 K. The rotational rate coefficients of SiO with para-H₂ (p-H₂) are compared with previous approximate results which were obtained using SiO-He PESs or scaled from SiO-He rate coefficients. Rovibrational state-to-state and total quenching cross sections and rate coefficients for initially excited SiO (v₁ = 1, j₁ = 0 and 1) in collisions with p-H₂ (v₂ = 0, j₂ = 0) and ortho-H₂ (o-H₂) (v₂ = 0, j₂ = 1) are also obtained. The application of the current collisional rate coefficients to astrophysics is briefly discussed.