Zhao Xiaorui, Shu Yinan, Zhang Linyao, Xu Xuefei, Truhlar Donald G
Center for Combustion Energy, Tsinghua University, Beijing 100084, P. R. China.
School of Aerospace Engineering, Tsinghua University, Beijing 100084, P. R. China.
J Chem Theory Comput. 2023 Mar 28;19(6):1672-1685. doi: 10.1021/acs.jctc.2c01260. Epub 2023 Mar 6.
Mixed quantum-classical nonadiabatic dynamics is a widely used approach to simulate molecular dynamics involving multiple electronic states. There are two main categories of mixed quantum-classical nonadiabatic dynamics algorithms, namely, trajectory surface hopping (TSH) in which the trajectory propagates on a single potential energy surface, interrupted by hops, and self-consistent-potential (SCP) methods, such as semiclassical Ehrenfest, in which propagation occurs on a mean-field surface without hops. In this work, we will illustrate an example of severe population leaking in TSH. We emphasize that such leaking is a combined effect of frustrated hops and long-time simulations that drive the final excited-state population toward zero as a function of time. We further show that such leaking can be alleviated-but not eliminated-by the fewest switches with time uncertainty TSH algorithm (here implemented in the SHARC program); the time uncertainty algorithm slows down the leaking process by a factor of 4.1. The population leaking is not present in coherent switching with decay of mixing (CSDM), which is an SCP method with non-Markovian decoherence included. Another result in this paper is that we find very similar results with the original CSDM algorithm, with time-derivative CSDM (tCSDM), and with curvature-driven CSDM (κCSDM). Not only do we find good agreement for electronically nonadiabatic transition probabilities but also we find good agreement of the norms of the effective nonadiabatic couplings (NACs) that are derived from the curvature-driven time-derivative couplings as implemented in κCSDM with the time-dependent norms of the nonadiabatic coupling vectors computed by state-averaged complete-active-space self-consistent field theory.
混合量子 - 经典非绝热动力学是一种广泛用于模拟涉及多个电子态的分子动力学的方法。混合量子 - 经典非绝热动力学算法主要有两类，即轨迹表面跳跃（TSH）算法，其中轨迹在单个势能面上传播，被跳跃中断；以及自洽势（SCP）方法，如半经典埃伦费斯特方法，其中传播发生在平均场表面上且无跳跃。在这项工作中，我们将展示一个TSH中严重布居泄漏的例子。我们强调，这种泄漏是受挫跳跃和长时间模拟的综合效应，随着时间推移，会使最终的激发态布居趋于零。我们进一步表明，通过具有时间不确定性的最少开关TSH算法（此处由SHARC程序实现），这种泄漏可以得到缓解，但无法消除；时间不确定性算法使泄漏过程减缓了4.1倍。在具有混合衰减的相干开关（CSDM）中不存在布居泄漏，CSDM是一种包含非马尔可夫退相干的SCP方法。本文的另一个结果是，我们发现原始的CSDM算法、时间导数CSDM（tCSDM）和曲率驱动CSDM（κCSDM）得到了非常相似的结果。我们不仅发现电子非绝热跃迁概率方面有很好的一致性，而且发现从κCSDM中实现的曲率驱动时间导数耦合导出的有效非绝热耦合（NACs）的范数与通过态平均完全活性空间自洽场理论计算的非绝热耦合矢量的时间相关范数也有很好的一致性。
