2009ApJ...706L..52Y

The reaction of CO with H⁺₃ and H₂D⁺ has been studied to investigate thermal rate coefficients and product branching ratios in the temperature range [20, 350] K, by using a direct ab initio molecular dynamics method. In trajectory simulations, the energies and forces are calculated using a scaling all correlation second-order Mφller-Plesset perturbation theory (SAC-MP2) method with the correlation consistent polarized valence triplet-zeta basis (cc-pVTZ).
Result. show that total thermal rate coefficients for both the CO + H⁺₃ and the CO + H₂D⁺ reactions have a weakly positive temperature dependence. At room temperature, the rate coefficients are predicted to be (1.42±0.03)x10^–9 cm3/molecule/s with a product branching ratio of [HOC⁺]/[HCO⁺] = 0.36±0.01 for the CO + H⁺₃reaction, and (1.26±0.03)x10^–9 cm3/molecule/s with the product branching ratios: 0.37±0.01 (([HOC⁺] + [DOC⁺])/([HCO⁺] + [DOC⁺])), 0.54 ± 0.02 ([DCO⁺]/[HCO⁺]), and 0.49±0.02 ([DOC⁺]/[HOC⁺]) for CO + H₂D⁺. The product branching ratios have a noticeable temperature dependence as well as a pronounced isotopic effect for the H/DOC⁺ product channel.