Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
J Chem Phys. 2011 Oct 28;135(16):164311. doi: 10.1063/1.3656242.
The three lowest (1A('), 2A('), and 1A('')) adiabatic potential energy surfaces (PESs) for the Br((2)P) + H(2) reactive system have been computed based on the multi-reference configuration interaction (MRCI) method including the Davidson's correction with a large basis set. These three adiabatic PESs have been transformed to a diabatic representation, leading to four coupling potentials. In addition, the spin-orbit matrix elements were also obtained using the Breit-Pauli Hamiltonian and the unperturbed MRCI wavefunctions in the Br + H(2) channel and the transition state region. Consequently, six coupling potentials were obtained and their characteristics were extensively discussed. Nonadiabatic quantum dynamics calculations for this system have been realized with these realistic diabatic potentials instead of previous semi-empirical diabatic potentials. Based on two-state model nonadiabatic calculations for the Br((2)P(3∕2), (2)P(1∕2)) + H(2) reaction, the Br((2)P(1∕2)) + H(2) reaction was found to show less reactivity than the Br((2)P(3∕2)) + H(2) reaction at collision energies beyond the threshold of the Br((2)P(3∕2)) + H(2) reaction. Our results are consistent with the previous studies on the XH(2) (X = F, Cl) system, which indicate that the adiabatically forbidden channel is dominant at low energies in the open-shell halogen atom plus H(2) reactions.
基于多参考组态相互作用（MRCI）方法，包括带有大基组的戴维森修正，我们计算了 Br((2)P) + H(2) 反应体系中三个最低的（1A('), 2A('), 和 1A(')）绝热势能面（PES）。这些三个绝热 PES 已经被转化为非绝热表示，导致四个耦合势。此外，使用 Breit-Pauli 哈密顿量和 Br + H(2) 通道和过渡态区域中的未微扰 MRCI 波函数，也获得了自旋轨道矩阵元。因此，得到了六个耦合势，并广泛讨论了它们的特性。使用这些现实的非绝热势而不是以前的半经验非绝热势，对该体系进行了非绝热量子动力学计算。基于 Br((2)P(3∕2), (2)P(1∕2)) + H(2) 反应的两态模型非绝热计算，发现在碰撞能超过 Br((2)P(3∕2)) + H(2) 反应的阈值时，Br((2)P(1∕2)) + H(2) 反应的反应性小于 Br((2)P(3∕2)) + H(2) 反应。我们的结果与之前关于 XH(2)（X = F, Cl）体系的研究一致，这表明在开壳层卤原子加 H(2) 反应中，在低能时绝热禁戒通道占主导地位。
