双分子亲核取代(SN2)反应是有机化学中最重要的一类反应，是研究多原子分子反应动力学的一个典型范例。实验和理论研究发现这类反应的反应机制极其复杂且相互竞争，其中量子效应不可忽略。现有的减维量子模型虽然可以考虑量子效应，但是不能准备描述各种重要反应机制。由于计算能力的限制，目前针对这类反应的精确全维量子动力学模拟存在巨大挑战，因此发展更为准确的高维量子模型和方法十分重要。本项目拟在原有6维量子动力学模型的基础上，发展适用于描述F-+CH3Y→ CH3F + Y- [Y= F, Cl, I]类SN2反应的9维量子动力学模型，以获得对该类反应更为准确的理论描述。在9维量子动力学模型下，使用含时波包方法研究F-+CH3Y类SN2反应的动力学，总结归纳不同形式能量以及不同振动模式对反应的促进作用，并为深入理解SN2反应机制提供新见解。

Bimolecular nucleophilic substitution (SN2) reaction, as one of the most important reactions in organic chemistry, is considered to be a prototypical candidate to study polyatomic reaction dynamics. Experimental and theoretical investigations showed that, on one hand, there exist competitions among different reaction mechanisms in this kind of reaction. These mechanisms are much more complicated than we have realized. On the other hand, the quantum effect is nonnegligible. Although the existed reduced-dimensional models take account of most of the quantum effect, they cannot describe accurately these important reaction mechanisms. Due to the limitation of computational capability, it is currently infeasible to perform a full-dimensional quantum dynamics study for the SN2 reactions. Therefore, it is urgent to develop more accurate reduced-dimensional models. In this project, a nine-dimensional quantum dynamics model for the F-+CH3Y→ CH3F + Y- [Y= F, Cl, I] SN2 reactions will be developed based the earlier six-dimensional dynamics model. Under the new nine-dimensional dynamics model, the quantum wave packet method is employed to study the reactions. We aim at summarizing the efficiencies of different kinds of energies on promoting the reactions and deepening our understanding on the reaction mechanisms of SN2 reactions.