A two-dimensional wavepacket study of the nonadiabatic dynamics of CH2BrCl.
A two-dimensional wavepacket study of the nonadiabatic dynamics of CH2BrCl.
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CH2BrCl 非绝热动力学的二维波包研究。
DOI：
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发表时间：
2008
影响因子：
2.9
通讯作者：
L. González
中科院分区：
文献类型：
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作者：
T. Rozgonyi;L. González
利用从头算多构型 MS-CASPT2 势能面上的二维波包传播研究了 CH2BrCl 生成 CH2Br + Cl 或 CH2Cl + Br 的非绝热光解动力学。使用三态非绝热模型，我们研究了导致两个竞争碎片通道的电子态以及两个最低激发态之间存在的锥形交叉如何影响解离率。在该模型中，我们发现 Br/Cl 支化比取决于照射波长。主要的 C-Br 碎裂发生在波长超过 200 nm 的情况下，而在吸收 170-180 nm 范围内的光子时，预计会发生分支比恒定为 0.4 的非绝热 C-Cl 解离。此外，我们在不到 100 fs 的时间内观察到完全的非绝热布居转移，即在波包到达圆锥形交叉点之前。因此，不存在三体 CH2 + Br + Cl 解离。
The nonadiabatic photodissociation dynamics of CH2BrCl into CH2Br + Cl or CH2Cl + Br is studied using two-dimensional wavepacket propagations on ab initio multiconfigurational MS-CASPT2 potential energy surfaces. Using a three-state diabatic model, we investigate the electronic states responsible for the two competing fragmentation channels and how the conical intersection present between the two lowest excited states affects the dissociation rate. Within this model, we find that the Br/Cl branching ratio depends on the irradiation wavelength. Predominant C-Br fragmentation occurs for wavelengths longer than 200 nm, while nonadiabatic C-Cl dissociation with a constant branching ratio of 0.4 is predicted upon absorption of photons in the range of 170-180 nm. Additionally, we observe complete nonadiabatic population transfer in less than 100 fs, that is, before the wavepacket can reach the conical intersection. As a consequence, there is no three-body CH2 + Br + Cl dissociation.