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Title: Collision-induced absorption with exchange effects and anisotropic interactions: Theory and application to H{sub 2} − H{sub 2}

We discuss three quantum mechanical formalisms for calculating collision-induced absorption spectra. First, we revisit the established theory of collision-induced absorption, assuming distinguishable molecules which interact isotropically. Then, the theory is rederived incorporating exchange effects between indistinguishable molecules. It is shown that the spectrum can no longer be written as an incoherent sum of the contributions of the different spherical components of the dipole moment. Finally, we derive an efficient method to include the effects of anisotropic interactions in the computation of the absorption spectrum. This method calculates the dipole coupling on-the-fly, which allows for the uncoupled treatment of the initial and final states without the explicit reconstruction of the many-component wave functions. The three formalisms are applied to the collision-induced rotation-translation spectra of hydrogen molecules in the far-infrared. Good agreement with experimental data is obtained. Significant effects of anisotropic interactions are observed in the far wing.
Authors:
; ;  [1]
  1. Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen (Netherlands)
Publication Date:
OSTI Identifier:
22416178
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 8; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ABSORPTION SPECTRA; ANISOTROPY; CALCULATION METHODS; COUPLING; DIPOLE MOMENTS; DIPOLES; HYDROGEN; MOLECULE COLLISIONS; MOLECULES; QUANTUM MECHANICS; ROTATION; SPHERICAL CONFIGURATION; WAVE FUNCTIONS