A quantum wave-packet study of intersystem crossing effects in the $O(P2,1,3,D21)+H2$ reaction Available to Purchase

We present for the first time an exact quantum study of spin–orbit-induced intersystem crossing effects in the title reaction. The time-dependent wave-packet method, combined with an extended split operator scheme, is used to calculate the fine-structure resolved cross section. The calculation involves four electronic potential-energy surfaces of the $A′1$ state [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)], the $A′3$ and the two degenerate $A″3$ states [S. Rogers, D. Wang, A. Kuppermann, and S. Wald, J. Phys. Chem. A 104, 2308 (2000)], and the spin–orbit couplings between them [B. Maiti, and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)]. Our quantum dynamics calculations clearly demonstrate that the spin–orbit coupling between the triplet states of different symmetries has the greatest contribution to the intersystem crossing, whereas the singlet-triplet coupling is not an important effect. A branch ratio of the spin state $Π3∕2$ to $Π1∕2$ of the product OH was calculated to be $∼2.75$⁠, with collision energy higher than $0.6eV$⁠, when the wave packet was initially on the triplet surfaces. The quantum calculation agrees quantitatively with the previous quasiclassical trajectory surface hopping study.