The isotopic product CD/CH branching ratios, thermal rate coefficients, as well as other dynamical quantities of the C(1D) + HD → CD(H) + H(D) reaction are investigated by detailed quasiclassical trajectory calculations on the highly accurate singlet ground-state (ã1A′) and the first excited-state (1A′′) global ab initio potential energy surfaces (PESs) recently constructed by us. The calculated CD/CH branching ratios are in reasonable agreement with experiment. The thermal rate coefficients in the temperature range of 200–1500 K are calculated, and the obtained values at room temperature are in very good agreement with available experimental data. The distinct topographical features between the present and previous PESs, which influence the CD/CH branching ratio, are also discussed. In addition, the effect of the 1A′′ PES is investigated, and the results show that the contribution from the 1A′′ PES to the total reactivity is rather noticeable.

Quasiclassical trajectory (QCT) calculations have been performed on a new global ab initio potential energy surface (PES) for the singlet ground state (11A′) of the CH2 reactive system. Our new PES can give a very good description of the well and asymptote regions, and particularly regions around conical intersections (CIs) and of van der Waals (vdW) interactions. The integral cross sections, differential cross sections, and product rovibrational state distributions for the C(1D) + H2 → CH + H reaction have been investigated in a wide range of collision energies. The present integral cross sections are much larger than the previous QCT results at low collision energies, which can be attributed to the differences of the PESs in the regions around the CIs and vdW complexes. The thermal rate coefficients in the temperature range 200–1500 K have also been calculated and very good agreement with experiment is obtained.