0000000000138902
AUTHOR
Susanta Mahapatra
A comparative account of quantum dynamics of the H+ + H2 reaction at low temperature on two different potential energy surfaces
Rotationally resolved reaction probabilities, integral cross sections, and rate constant for the H+ + H2 (v = 0, j = 0 or 1) → H2 (v′ = 0, j′) + H + reaction are calculated using a time-independent quantum mechanical method and the potential energy surface of Kamisaka et al. [J. Chem. Phys.116, 654 (2002)] (say KBNN PES). All partial wave contributions of the total angular momentum, J, are included to obtain converged cross sections at low collision energies and rate constants at low temperatures. In order to test the accuracy of the KBNN PES, the results obtained here are compared with those obtained in our earlier work [P. Honvault et al. , Phys. Rev. Lett.107, 023201 (2011)] using the ac…
Huge Quantum Symmetry Effect in the O + O2 Exchange Reaction.
We report extensive, full quantum-mechanical calculations for the (16)O + (16)O(16)O → (16)O(16)O + (16)O collisions, for both inelastic and atom exchange processes, using a time-independent method based on hyperspherical coordinates. The rates obtained in the present study are much larger than the previously reported ones for this system. The discrepancy is attributed to a huge symmetry effect that was missing in the studies so far. This effect differs from the well-known isotope effect. Importance of this quantum effect is further confirmed by comparison with results for the (16)O + (18)O(18)O → (16)O(18)O + (18)O, exchange reaction.
Quantum dynamics of 16O + 36O2 and 18O + 32O2 exchange reactions
We present quantum dynamical investigations of (16)O + (36)O2 and (18)O + (32)O2 exchange reactions using a time-independent quantum mechanical method and an accurate global potential energy surface of ozone [Dawes et al., J. Chem. Phys. 135, 081102 (2011)]. Initial state-selected integral cross sections, rate constants, and Boltzmann averaged thermal rate constants are obtained and compared with earlier experimental and theoretical results. The computed thermal rate constants for the oxygen exchange reactions exhibit a negative temperature dependence, as found experimentally. They are in better agreement with the experiments than the previous studies on the same reactions.
Quantum Dynamics of the 18O + 36O2 Collision Process
We report full quantum cross sections and rate constants for the (18)O + (36)O2 → (36)O2 + (18)O collision process. This constitutes to the best of our knowledge the first dynamical study of the (18)O(18)O(18)O system, with three identical (18)O oxygen atoms. We emphasize the comparison with the (16)O + (32)O2 collision as this latter presents the exact same features as the one treated here, except the consistent change of mass for all three atoms. We find very similar behaviors in the cross sections, and we confirm that the rates are faster when three identical nuclei are involved. In particular, we cannot dynamically study this system with classical trajectory methods, and we have to incl…
Differential Cross Sections and Product Rovibrational Distributions for (16)O + (32)O2 and (18)O + (36)O2 Collisions.
We report rotationally resolved opacity functions, product rotational distributions, and differential cross sections for the (16)O + (16)O(16)O (v = 0,j = 1) → (16)O(16)O (v' = 0,j') + (16)O and (18)O + (18)O(18)O (v = 0,j = 1) → (18)O(18)O (v' = 0,j') + (18)O collisions calculated by a time-independent quantum mechanical method employing one of the latest potential energy surface of ozone [ Dawes ; et al. J. Chem. Phys. 2013 , 139 , 201103 ]. The results obtained for both collisional systems in the energy range 0.001-0.2 eV are examined, and interesting mass scaling effects have been discovered. The shapes of product angular distributions suggest a transition from an indirect to a direct s…