Collision induced dissociation of H₂⁺ and D ₂⁺ with H₂ using a surface hopping trajectory method

The collision induced dissociation (CID) and charge transfer (CT) cross sections have been determined for H₂⁺ and D ₂⁺ colliding with H₂ using a surface hopping trajectory method. Approximately 40 000 trajectories have been analyzed for collisions at 4.0, 6.0, and 8.0 eV (center of mass) and for H₂ ⁺ (D₂⁺) in vibrational states from 0 to 10. Our results are consistent with the recent experiments of Guyon, Baer, Cole, and Govers [Chem. Phys. 119, 145 (1988) ]. However we have come to a different understanding of the mechanism for dissociation. We find that there are two pathways for CID: (1) formation of a H₃⁺ intermediate followed by dissociation and (2) direct dissociation of a H₄ ⁺ transition state via vibrational excitation. The H₃ ⁺ intermediate pathway predominates at low collisional and low H ₂⁺ (D₂⁺) vibrational energies.