Rotational excitation of NCO induced by collision with Helium at low temperatures

Abstract

We report the cross sections and the transitional rates of the first 11 rotational levels of the NCO induced by collision with He at low temperatures. For this purpose, we have calculated the potential energy surface (PES), i.e transitional structure between the NCO(X1Σ) and He() by using the coupled cluster singles and doubles perturbed by triple excitations (CCSD(T)). The augmented correlation consistent polarized valence triple zeta (AVTZ) basis set to which we have associated the mid-bond functions, between the molecule and the projectile for a better description of the van der Waals interaction, was used. The PES was interpolated by the Legendre polynomials, analytically fitted, then used for the evaluation of the integral state-to-state rotational transitions cross sections in the close-coupling approach. The rate coefficients were subsequently computed for low kinetic temperature (T 150K).