H2 ortho para rate Lique+ 2012
rates fairly close to Sun Dalgarno 1994 (which we now use) but extend over greater range, to higher temperature. Paper is not on ADS right now
THE JOURNAL OF CHEMICAL PHYSICS 137, 154303 (2012)
Ortho–para-H2 conversion by hydrogen exchange: Comparison
of theory and experiment
François Lique,1,a) Pascal Honvault,2 and Alexandre Faure3
1LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre, France
2Laboratoire ICB, UMR 6303, CNRS-Université de Bourgogne, 21078 Dijon cedex, France and
UFR Sciences et Techniques, Université de Franche-Comté, 25030 Besançon Cedex, France
3UJF-Grenoble 1/CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274,
Grenoble F-38041, France
(Received 27 July 2012; accepted 28 September 2012; published online 16 October 2012)
We report fully-quantum time-independent calculations of cross sections and rate coefficients for the
collisional (de)excitation of H2 by H. Our calculations are based on the H3 global potential energy
surface of Mielke et al. [J. Chem. Phys. 116, 4142 (2002)]. The reactive hydrogen exchange channels
are taken into account. We show that the ortho-para and para-ortho conversion of H2 are significant
processes at temperatures above ?300 K and for the last process we provide the first comparison
with available experimental rate coefficients between 300 and 444 K. The good agreement between
theory and experiment is a new illustration of our detailed understanding of the simplest chemical
reaction. The importance of the ortho–para-H2 conversion by hydrogen exchange in astrophysics is
discussed. © 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4758791]