Theoretical calculation of the vib-rotational interaction potential and the scattering cross section for the Ar-H2 (D2, T2) collision system

Abstract

Based on the ab initio coupled-cluster CCSD(T) method in quantum mechanics, the charge distribution of Ar atom and its vib-rotational interaction with H2 molecule are calculated using augmented correlation consistent basis sets aug-cc-pV5Z and 3s3p2d1f1g Gaussian bonding function, and the basis set superposition error (BSSE) is eliminated using Boy and Bernardi's full counterpoise method. Afterwards, the analytical expression of the interaction potential of the Ar-H2 system is fitted with Tang-Toennies potential function. With this interaction potential, the scattering cross section of Ar-H2(D2, T2) collision system is calculated by using close-coupling method when the incident energy of Ar atoms is 83 meV. The calculated differential cross section of Ar-D2 collision system is consistent with the experimental results. Calculated result and analysis show that the dispersion energy plays a key role in the long-range attractive potential scattering, and the exchange energy plays an important role in the short-range repulsive potential scattering. The direction of the radial dipole of the Ar-H2 (D2, T2) collision system is turned twice in the range of impact parameters from 0.27 to 0.47 nm.