Brian Dominikus, Sun Xiang
Division of Arts and Sciences, NYU Shanghai, 1555 Century Avenue, Shanghai 200122, China.
NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshan Road North, Shanghai 200062, China.
J Chem Theory Comput. 2021 Apr 13;17(4):2065-2079. doi: 10.1021/acs.jctc.0c01250. Epub 2021 Mar 9.
Instantaneous Marcus theory (IMT) offers a way for capturing the time-dependent charge transfer (CT) rate coefficient in nonequilibrium photoinduced CT processes, where the system was photoexcited from its equilibrated ground state vertically to the excitonic state, followed by an electronic transition to the CT state. As derived from the linearized semiclassical nonequilibrium Fermi's golden rule (LSC NE-FGR), the original IMT requires expensive all-atom nonequilibrium molecular dynamics (NEMD) simulations. In this work, we propose computationally efficient linear-response and nonlinear-response formulations for IMT rate calculations, which only require equilibrium molecular dynamics simulations. The linear- and nonlinear-response IMT methods were tested to predict the transient behavior in the photoinduced CT dynamics of the carotenoid-porphyrin-C molecular triad solvated in explicit tetrahydrofuran. Our result demonstrated that the nonlinear-response IMT is in excellent agreement with the benchmark NEMD for all cases investigated here, whereas the linear-response IMT predicts the correct trend for all cases but overestimates the transient CT rate in one case involving a significant nonequilibrium relaxation. This mild breakdown of linear-response IMT is due to neglecting the higher-order terms in the exact nonlinear-response IMT. Taking advantage of time translational symmetry, the linear- and nonlinear-response approaches were demonstrated to be able to reduce the computational cost by 80% and 60% compared with NEMD simulations, respectively. Thus, we highly recommend the readily applicable and accurate nonlinear-response IMT approach for simulating nonequilibrium CT processes in complex molecular systems in the condensed phase.
瞬态马库斯理论（IMT）为捕捉非平衡光致电荷转移（CT）过程中随时间变化的电荷转移速率系数提供了一种方法，在该过程中，系统从其平衡基态垂直光激发到激子态，随后发生电子跃迁到CT态。从线性化半经典非平衡费米黄金规则（LSC NE-FGR）推导而来，原始的IMT需要昂贵的全原子非平衡分子动力学（NEMD）模拟。在这项工作中，我们提出了用于IMT速率计算的计算效率高的线性响应和非线性响应公式，这些公式仅需要平衡分子动力学模拟。对线性和非线性响应IMT方法进行了测试，以预测溶解在显式四氢呋喃中的类胡萝卜素-卟啉-C分子三联体光致CT动力学中的瞬态行为。我们的结果表明，非线性响应IMT在此处研究的所有情况下都与基准NEMD非常吻合，而线性响应IMT在所有情况下都预测了正确的趋势，但在一个涉及显著非平衡弛豫的情况下高估了瞬态CT速率。线性响应IMT的这种轻微失效是由于忽略了精确非线性响应IMT中的高阶项。利用时间平移对称性，与NEMD模拟相比，线性和非线性响应方法分别能够将计算成本降低80%和60%。因此，我们强烈推荐易于应用且准确的非线性响应IMT方法用于模拟凝聚相中复杂分子系统的非平衡CT过程。
