Abstract
Three-dimensional potential energy surface (3D-PES) of the HNS-He interacting system in Jacobi coordinates is mapped using high-level ab initio theory. These computations are performed at the explicitly correlated coupled cluster method with single, double and perturbative triple excitations (CCSD(T)-F12) in conjunction with the augmented correlation-consistent aug-cc-pVTZ basis set. The 3D-PES is incorporated into quantum dynamical computations to treat the nuclear motions, where HNS is considered as a rigid rotator colliding with He. Cross-sections for transitions among the first twenty nine rotational levels of HNS (up to j(KaKc) = 9(2,8)) are calculated using the quantum exact close-coupling method for total energies < 1000 cm(-1) and using the coupled state approximation for higher energies. Collisional rate constants for temperatures ranging from 5 to 200 K are deduced. A clear propensity rule in favour of Delta j = -2 rotational transitions is observed. These rate coefficients are of great importance for the detection of HNS in interstellar medium.