Hu Zhubin, Brian Dominikus, Sun Xiang
Division of Arts and Sciences, NYU Shanghai, 1555 Century Avenue, Shanghai 200122, China.
J Chem Phys. 2021 Sep 28;155(12):124105. doi: 10.1063/5.0064763.
Model Hamiltonians constructed from quantum chemistry calculations and molecular dynamics simulations are widely used for simulating nonadiabatic dynamics in the condensed phase. The most popular two-state spin-boson model could be built by mapping the all-atom anharmonic Hamiltonian onto a two-level system bilinearly coupled to a harmonic bath using the energy gap time correlation function. However, for more than two states, there lacks a general strategy to construct multi-state harmonic (MSH) models since the energy gaps between different pairs of electronic states are not entirely independent and need to be considered consistently. In this paper, we extend the previously proposed approach for building three-state harmonic models for photoinduced charge transfer to the arbitrary number of electronic states with a globally shared bath and the system-bath couplings are scaled differently according to the reorganization energies between each pair of states. We demonstrate the MSH model construction for an organic photovoltaic carotenoid-porphyrin-C molecular triad dissolved in explicit tetrahydrofuran solvent. Nonadiabatic dynamics was simulated using mixed quantum-classical techniques, including the linearized semiclassical and symmetrical quasiclassical dynamics with the mapping Hamiltonians, mean-field Ehrenfest, and mixed quantum-classical Liouville dynamics in two-state, three-state, and four-state harmonic models of the triad system. The MSH models are shown to provide a general and flexible framework for simulating nonadiabatic dynamics in complex systems.
由量子化学计算和分子动力学模拟构建的模型哈密顿量被广泛用于模拟凝聚相中的非绝热动力学。最流行的两态自旋玻色子模型可以通过使用能隙时间关联函数将全原子非谐哈密顿量双线性映射到与简谐浴耦合的两能级系统来构建。然而，对于多于两个态的情况，由于不同电子态对之间的能隙并非完全独立且需要一致考虑，因此缺乏构建多态简谐（MSH）模型的通用策略。在本文中，我们将先前提出的用于构建光诱导电荷转移三态简谐模型的方法扩展到任意数量的电子态，采用全局共享浴，并且根据每对态之间的重组能对系统 - 浴耦合进行不同的缩放。我们展示了溶解在明确的四氢呋喃溶剂中的有机光伏类胡萝卜素 - 卟啉 - C分子三联体的MSH模型构建。使用混合量子 - 经典技术模拟非绝热动力学，包括线性化半经典和对称准经典动力学以及映射哈密顿量、平均场埃伦费斯特和混合量子 - 经典刘维尔动力学，应用于三联体系统的两态、三态和四态简谐模型。结果表明，MSH模型为模拟复杂系统中的非绝热动力学提供了一个通用且灵活的框架。
