Jiang Xiang, Zheng Qijing, Lan Zhenggang, Saidi Wissam A, Ren Xinguo, Zhao Jin
ICQD/Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety, and MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China.
Sci Adv. 2021 Mar 5;7(10). doi: 10.1126/sciadv.abf3759. Print 2021 Mar.
We develop an ab initio nonadiabatic molecular dynamics (NAMD) method based on plus real-time Bethe-Salpeter equation ( + rtBSE-NAMD) for the spin-resolved exciton dynamics. From investigations on MoS, we provide a comprehensive picture of spin-valley exciton dynamics where the electron-phonon (e-ph) scattering, spin-orbit interaction (SOI), and electron-hole (e-h) interactions come into play collectively. In particular, we provide a direct evidence that e-h exchange interaction plays a dominant role in the fast valley depolarization within a few picoseconds, which is in excellent agreement with experiments. Moreover, there are bright-to-dark exciton transitions induced by e-ph scattering and SOI. Our study proves that e-h many-body effects are essential to understand the spin-valley exciton dynamics in transition metal dichalcogenides and the newly developed + rtBSE-NAMD method provides a powerful tool for exciton dynamics in extended systems with time, space, momentum, energy, and spin resolution.
我们基于含时密度泛函理论（TDDFT）加实时贝叶斯 - 萨尔皮特方程（ + rtBSE - NAMD）开发了一种用于自旋分辨激子动力学的从头算非绝热分子动力学（NAMD）方法。通过对二硫化钼（MoS₂）的研究，我们给出了自旋 - 能谷激子动力学的全面图景，其中电子 - 声子（e - ph）散射、自旋 - 轨道相互作用（SOI）以及电子 - 空穴（e - h）相互作用共同起作用。特别是，我们提供了直接证据表明e - h交换相互作用在几皮秒内的快速能谷去极化中起主导作用，这与实验结果高度吻合。此外，存在由e - ph散射和SOI诱导的亮激子到暗激子的跃迁。我们的研究证明，e - h多体效应对于理解过渡金属二卤化物中的自旋 - 能谷激子动力学至关重要，并且新开发的 + rtBSE - NAMD方法为具有时间、空间、动量、能量和自旋分辨率的扩展系统中的激子动力学提供了一个强大的工具。
