Wei Liu

2024

1. Arxiv

   Enhancement of Chiral-Induced Spin Selectivity via Circularly Polarized Light

   Wei Liu, Jingqi Chen, and Wenjie Dou

   arXiv preprint arXiv:2402.00903, 2024

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   The notion of chiral-induced spin selectivity (CISS) has attracted intensive research interest recently. However, the practical applications of the CISS effects face challenges due to relatively low spin polarization. In this Letter, we propose a non-perturbative theory illustrating how circularly polarized (CP) light enhances CISS effects through strong light-matter interactions. We introduce a Floquet electronic friction model to study the nonadiabatic dynamics and spin transport through a chiral molecule in a molecule junction subjected to external driving. Our results show that the interplay of the nonadiabatic effects and light-matter interactions can significantly (>90%) enhance electron spin polarization under CP light. Our predictions can be very useful in experiments for using CP light to control spin current in chiral molecular junctions.

2. JCTC

   Nonadiabatic dynamics near metal surfaces with periodic drivings:A generalized surface hopping in Floquet representation

   Yu Wang, Vahid Mosallanejad, Wei Liu, and Wenjie Dou

   Journal of Chemical Theory and Computation, 2024

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   With light–matter interaction extending into the strong regime, as well as rapid development of laser technology, systems subjecting to a time-periodic perturbation have attracted broad attention. Floquet theorem and Floquet time-independent Hamiltonian are powerful theoretical frameworks to investigate the systems subjected to time-periodic drivings. In this study, we extend the previous generalized surface hopping (SH) algorithm near a metal surface (J. Chem. Theory Comput. 2017, 13, 6, 2430–2439) to the Floquet space, and hence, we develop a generalized Floquet representation-based SH (FR-SH) algorithm. Here, we consider an open quantum system with fast drivings. We expect that the present algorithm will be useful for understanding the chemical processes of molecules under time-periodic driving near the metal surface.

2023

1. Arxiv

   Polaritons under Extensive Disordered Molecular Rotation in Optical Cavities

   Wei Liu, Jingqi Chen, and Wenjie Dou

   arXiv preprint arXiv:2312.16891, 2023

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   This study investigates the dynamic behavior of polaritons in an optical cavity containing one million molecules, emphasizing the influence of molecular rotation and level disorder on the coupling between molecules and photons. Through rigorous theoretical simulations and numerical analyses, we systematically explore the formation and spectral characteristics of polaritons in this complex environment. Our findings reveal that the rotational motion of molecules significantly affects the electromagnetic field distribution within the cavity, leading to distinct alterations in polariton prop- erties. Simultaneously, the presence of level disorder induces diverse energy level structures, in- fluencing the energy distribution of polaritons. The comprehensive examination of these factors provides valuable insights into the intricate interplay between molecules and photons in large-scale cavity systems. This research not only advances the fundamental understanding of molecular photon coupling but also offers theoretical guidance for practical applications in the design and exploration of optical cavities.

2. Arxiv

   Optical Regulation of Chiral-Induced Spin Selectivity

   Wei Liu, Jingqi Chen, and Wenjie Dou

   arXiv preprint arXiv:2310.10929, 2023

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   We present a non-perturbative theory that describes how light regulates chiral-induced spin selectivity (CISS) from the perspective of strong light-matter interactions. The research results indicate that 1) light can have opposite effects on the CISS, 2) the difference in CISS is caused by the steady states of nuclei coupled to spin electrons and 3) this steady state differences are caused by the different light-induced Lorentz forces felt by spin-up and spin-down electrons. The fundamental reason for these results is the impact of light on spin-orbital coupling (SOC), which is a complex process. This theoretical framework is verified by the calculations of Floquet SOC non-adiabatic nuclear dynamics.

3. JCP

   Predicting rate kernels via dynamic mode decomposition

   Wei Liu, Zi-Hao Chen, Yu Su, Yao Wang, and Wenjie Dou

   The Journal of Chemical Physics, 2023

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   Simulating dynamics of open quantum systems is sometimes a significant challenge, despite the availability of various exact or approximate methods. Particularly when dealing with complex systems, the huge computational cost will largely limit the applicability of these methods. We investigate the usage of dynamic mode decomposition (DMD) to evaluate the rate kernels in quantum rate processes. DMD is a data-driven model reduction technique that characterizes the rate kernels using snapshots collected from a small time window, allowing us to predict the long-term behaviors with only a limited number of samples. Our investigations show that whether the external field is involved or not, the DMD can give accurate prediction of the result compared with the traditional propagations, and simultaneously reduce the required computational cost.

4. Arxiv

   Floquet Nonadiabatic Nuclear Dynamics with Photoinduced Lorenz-Like Force in Quantum Transport

   Jingqi Chen, Wei Liu, and Wenjie Dou

   arXiv preprint arXiv:2308.12660, 2023

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   In our recent paper [Mosallanejad et al., Phys. Rev. B 107(18), 184314, 2023], we have derived a Floquet electronic friction model to describe nonadiabatic molecular dynamics near metal surfaces in the presence of periodic driving. In this work, we demonstrate that Floquet driving can introduce an anti-symmetric electronic friction tensor in quantum transport, resulting in circular motion of the nuclei in the long time limit. Furthermore, we show that such a Lorentz-like force strongly affects nuclear motion, at lower voltage bias, Floquet driving can increase the temperature of nuclei; at larger voltage bias, Floquet driving can decrease the temperature of nuclei. In addition, Floquet driving can affect electron transport strenuously. Finally, we show that there is an optimal frequency that maximizes electron current. We expect that the Floquet electronic friction model is a powerful tool to study nonadiabatic molecular dynamics near metal surfaces under Floquet driving in complex systems.