Inelastic vibrational dynamics of CS in collision with H2 using a full-dimensional potential energy surface

Abstract

We report a six-dimensional (6D) potential energy surface (PES) for the CS–H₂ system computed using high-level electronic structure theory and fitted using a hybrid invariant polynomial method. Full-dimensional quantum close-coupling scattering calculations have been carried out using this potential for rotational and, for the first time, vibrational quenching transitions of CS induced by H₂. State-to-state cross sections and rate coefficients for rotational transitions in CS from rotational levels j₁ = 0–5 in the ground vibrational state are compared with previous theoretical results obtained using a rigid-rotor approximation. For vibrational quenching, state-to-state and total cross sections and rate coefficients were calculated for the vibrational transitions in CS(v₁ = 1,j₁) + H₂(v₂ = 0,j₂) → CS(v₁′ = 0,j₁′) + H₂(v₂′ = 0,j₂′) collisions, for j₁ = 0–5. Cross sections for collision energies in the range 1 to 3000 cm⁻¹ and rate coefficients in the temperature range of 5 to 600 K are obtained for both para-H₂ (j₂ = 0) and ortho-H₂ (j₂ = 1) collision partners. Application of the computed results in astrophysics is also discussed.