Vibration–rotation line shifts for 1Σg+ H2 (v, J)–1S He computed via close coupling: temperature dependence

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Abstract
The density-shifting of vibration–rotation transitions of H2 perturbed by He was computed (as a function of temperature) with no adjustable parameters. The calculation was carried out using the framework of the impact theory of Baranger with S-matrix elements obtained via close-coupling calculations which incorporated the ab initio H2–He system potential of Tsapline, Kutzelnigg, Raczkowski, and Lester [Chem. Phys. Lett. 47, 45 (1977)]. Vibrational and rotational inelasticity were neglected in the calculations; nevertheless good agreement with experimental data was obtained, up to moderate temperatures, for the density shift. A much poorer comparison was obtained for the density broadening.