Eur. Phys. J. D (2016) 70: 236
https://doi.org/10.1140/epjd/e2016-70114-9

Regular Article

A test of H₂-He potential energy surfaces

¹ Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, Bât. 11B, 35042 Rennes, France
² Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5/7, 87-100 Torun, Poland

^a e-mail: franck.thibault@univ-rennes1.fr

Received: 19 February 2016
Received in final form: 17 August 2016
Published online: 10 November 2016

Abstract

The close-coupling method is used to calculate purely rotational relaxation rates and pressure broadening and shifting coefficients for H₂-He collisions, in order to test various potential energy surfaces. Downward rate coefficients k_3→1(T) and k_2→0(T) are compared with experimental data, but the subtle differences in the potential energy surfaces are hardly reflected in these rates. Helium pressure broadening and shifting generalized cross sections for the isotropic Raman Q(1) lines of the fundamental bands of D₂ and H₂ as well as the purely rotational Stokes S₀(1) line of H₂ are therefore also considered. While these spectroscopic characteristics are much more sensitive to the precise form of the interaction potential, a proper validation cannot be performed without taking into account the influence of the translational motion on the molecular line shapes. After including this, it is found that the potential energy surface of Bakr, Smith and Patkowski [B.W. Bakr, D.G.A. Smith, K. Patkowski, J. Chem. Phys. 139, 144305 (2013)] allows the best reproduction of the experimental data.