由经验时间尺度主导的损耗机制的存在会深刻影响系统的动力学与光谱特性。然而，将这些效应及其与系统相互作用的热耗散环境的耦合纳入考量，被证明极具挑战性。我们近期开发了路径积分林德布拉德动力学（path integral Lindblad dynamics, PILD）方法，将数值严格的路径积分模拟与林德布拉德动力学相结合，以解释这类经验损耗机制。在本研究中，我们利用PILD方法研究手性分子聚集体与激子极化子的吸收光谱和圆二色（circular dichroism, CD）光谱。我们证明，损耗对两种系统中特定态的影响不仅取决于态的对称性，还取决于系统、损耗机制与耗散环境之间复杂的“相互作用”。我们首次对限制在微腔中的手性分子聚集体的CD光谱开展了数值探索。仅激子聚集体本身的CD光谱就无法用激子手性（exciton chirality, EC）规则这类简单理论来理解，而极化子分子的CD光谱则更为复杂。此外，经验损耗对极化子CD光谱的影响呈现出高度的位点依赖性：损耗型微腔的影响与泄漏激发的分子的影响在性质上存在差异。我们借助路径积分林德布拉德动力学框架，对其中部分效应进行了深入探究。
英文摘要：
The presence of loss mechanisms governed by empirical time-scales affect the dynamics and spectra of systems in profound ways. However, incorporation of these effects and their interaction with the thermal dissipative environments interacting with the system prove to be challenging. We have recently developed the path integral Lindblad dynamics (PILD) method to combine numerically rigorous path integral simulations with Lindblad dynamics to account for such empirical loss mechanisms. In this work, we utilize the PILD method to study the absorption and circular dichroism spectra of chiral molecular aggregates and excitonic polaritons. We demonstrate that the effect of loss on particular states in both systems can differ not just on the basis of the symmetries of the state but also on the basis of complicated "interactions" of the system and the loss mechanism with the dissipative environments. We present probably the first numerical exploration of the CD spectrum of chiral molecular aggregates confined in a cavity. While the CD spectrum of just the excitonic aggregates itself is not amenable to simplistic understanding like the exciton chirality (EC) rule, the CD spectrum of polaritonic molecules is even more complex. Additionally, the impact of empirical loss on the polaritonic CD spectrum seems to be highly site-dependent. The impact of a lossy cavity is qualitatively different from the impact of a molecule that leaks the excitation. We explore some of those effects in depth leveraging the framework of path integral Lindblad dynamics.
Davydov-Type Excitonic Effects on the Absorption Spectra of Parallel-Stacked and Herringbone Aggregates of Pentacene: Time-Dependent Density-Functional Theory and Time-Dependent Density-Functional Tight Binding
Time-Dependent Density Matrix Renormalization Group Algorithms for Nearly Exact Absorption and Fluorescence Spectra of Molecular Aggregates at Both Zero and Finite Temperature
Queens College, City University of New York（纽约市立大学皇后学院）；Graduate Center, City University of New York（纽约市立大学研究生院）；Goethe University Frankfurt（法兰克福歌德大学）；Institute of Chemistry, Academia Sinica（中央研究院化学研究所）；National Center for Theoretical Sciences（国家理论科学中心）；University of California, Riverside（加州大学河滨分校）
