title: Ortho-para H₂ conversion by proton exchange at low temperature: an accurate quantum mechanical study.
abstract: We report extensive, accurate fully quantum, time-independent calculations of cross sections at low collision energies, and rate coefficients at low temperatures for the H⁺ + H₂(v = 0, j) → H⁺ + H₂(v = 0, j') reaction. Different transitions are considered, especially the ortho-para conversion (j = 1 → j' = 0) which is of key importance in astrophysics. This conversion process appears to be very efficient and dominant at low temperature, with a rate coefficient of 4.15 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ at 10 K. The quantum mechanical results are also compared with statistical quantum predictions and the reaction is found to be statistical in the low temperature regime (T < 100 K).
authors.affiliation: Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 5209, Université de Bourgogne, 21078 Dijon Cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Honvault
authors.forename: M
authors.initials: M
authors.lastname: Jorfi
authors.forename: T
authors.initials: T
authors.lastname: González-Lezana
authors.forename: A
authors.initials: A
authors.lastname: Faure
authors.forename: L
authors.initials: L
authors.lastname: Pagani