Quantum dynamics of the C(1D)+HD and C(1D)+n-D2 reactions on the a? 1A' and b? 1A? surfaces

Abstract

We present the Born-Oppenheimer, quantum dynamics of the reactions C(D-1)+HD andC(D-1)+n-D-2 on the uncoupled potential energy surfaces a approximate to (1)A(') and b approximate to (1)A('), considering the Coriolis interactions and the nuclear-spin statistics. Using the real wavepacket method, we obtain initial-state-resolved probabilities, cross sections, isotopic branching ratios, and rate constants. Similarly to the C+n-H-2 reaction, the probabilities present many a approximate to (1)A(') or few b approximate to (1)A(') sharp resonances, and the cross sections are very large at small collision energies and decrease at higher energies. At any initial condition, the C+HD reaction gives preferentially the CD+H products. Thermal cross sections, isotopic branching ratios, and rate constant k vary slightly with temperature and agree very well with the experimental values. At 300 K, we obtain for the various products k(CH+H)=(2.45 +/- 0.08)x10(-10), k(CD+H)=(1.19 +/- 0.04)x10(-10), k(CH+D)=(0.71 +/- 0.02)x10(-10), k(CD+D)=(1.59 +/- 0.05)x10(-10) cm(3) s(-1), and k(CD+H)/k(CH+D)=1.68 +/- 0.01. The b approximate to (1)A(') contribution to cross sections and rate constants is always large, up to a maximum value of 62% for a rotationally resolved C+D-2 rate constant. The upper b approximate to (1)A(') state is thus quite important in the C(D-1) collision with H-2 and its deuterated isotopes, as the agreement between theory and experiment shows.