Han Daeho, Akimov Alexey V
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
J Chem Theory Comput. 2024 Jun 25;20(12):5022-5042. doi: 10.1021/acs.jctc.4c00343. Epub 2024 Jun 5.
In this work, we report our implementation of several independent-trajectory mixed-quantum-classical (ITMQC) nonadiabatic dynamics methods based on exact factorization (XF) in the Libra package for nonadiabatic and excited-state dynamics. Namely, the exact factorization surface hopping (SHXF), mixed quantum-classical dynamics (MQCXF), and mean-field (MFXF) are introduced. Performance of these methods is compared to that of several traditional surface hopping schemes, such as the fewest-switches surface hopping (FSSH), branching-corrected surface hopping (BCSH), and the simplified decay of mixing (SDM), as well as conventional Ehrenfest (mean-field, MF) method. Based on a comprehensive set of 1D model Hamiltonians, we find the ranking SHXF ≈ MQCXF > BCSH > SDM > FSSH ≫ MF, with the BCSH sometimes outperforming the XF methods in terms of describing coherences. Although the MFXF method can yield reasonable populations and coherences for some cases, it does not conserve the total energy and is therefore not recommended. We also find that the branching correction for auxiliary trajectories is important for the XF methods to yield accurate populations and coherences. However, the branching correction can worsen the quality of the energy conservation in the MQCXF. Finally, we find that using the time-dependent Gaussian width approximation used in the XF methods for computing decoherence correction can improve the quality of energy conservation in the MQCXF dynamics. The parameter-free scheme of Subotnik for computing the Gaussian widths is found to deliver the best performance in situations where such widths are not known a priori.
在这项工作中，我们报告了我们在用于非绝热和激发态动力学的Libra软件包中基于精确因子分解（XF）实现的几种独立轨迹混合量子经典（ITMQC）非绝热动力学方法。具体而言，引入了精确因子分解表面跳跃（SHXF）、混合量子经典动力学（MQCXF）和平均场（MFXF）方法。将这些方法的性能与几种传统表面跳跃方案进行了比较，例如最少开关表面跳跃（FSSH）、分支校正表面跳跃（BCSH）和混合简化衰减（SDM），以及传统的埃伦费斯特（平均场，MF）方法。基于一组全面的一维模型哈密顿量，我们发现排序为SHXF≈MQCXF>BCSH>SDM>FSSH≫MF，在描述相干性方面，BCSH有时优于XF方法。尽管MFXF方法在某些情况下可以产生合理的布居数和相干性，但它不守恒总能量，因此不推荐使用。我们还发现，辅助轨迹的分支校正对于XF方法产生准确的布居数和相干性很重要。然而，分支校正会使MQCXF中的能量守恒质量变差。最后，我们发现使用XF方法中用于计算退相干校正的含时高斯宽度近似可以提高MQCXF动力学中的能量守恒质量。发现Subotnik用于计算高斯宽度的无参数方案在事先不知道此类宽度的情况下表现最佳。
