Theoretical study of the stereodynamics of the reactions of D− + H2 → H− + HD and H− + D2 → D− + HD

The product rotational polarization of the ion-molecule reactions of D− + H2 → H− + HD and H− +  D2 → D− + HD has been calculated by means of the quasi-classical trajectory method on a potential energy surface (PES) constructed by Panda and Sathyamurthy [J. Chem. Phys. 121, 9343 (2004)]. Comparing the dynamics of D− + H2 → H− + HD with H− + D2 → D− + HD, four polarization dependent generalized differential cross-sections (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt), (2π/σ)(dσ21−/dωt) have been presented in the center of mass frame, respectively. The distribution of dihedral angle p(ϕr), the distribution of angle between k and j′, p(θr), and the angular distribution of product rotational vectors in the form of polar plots in θr and ϕr are calculated as well. A pronounced isotopic effect is also revealed. It may be ascribed to the significant difference of the effective potential barrier height or the difference of the mass factor in the two reactions.