Department of Chemistry, Technische Universität München, Garching D-85747, Germany.
School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom.
J Chem Phys. 2019 Dec 28;151(24):244116. doi: 10.1063/1.5132341.
We have extended the multiconfigurational Ehrenfest (MCE) approach to investigate the dynamics of a one-dimensional Holstein molecular crystal model. It has been shown that the extended MCE approach yields results in perfect agreement with benchmark calculations by the hierarchy equations of motion method. The accuracies of the MCE approach in describing the dynamical properties of the Holstein polaron over a wide range of exciton transfer integrals and exciton-phonon couplings are carefully examined by a detailed comparison with the fully variational multiple Davydov D ansatz. It is found that while the MCE approach and the multi-D ansatz produce almost exactly the same results for a small transfer integral, the results obtained by the multi-D ansatz start to deviate from those by the MCE approach at longer times for a large transfer integral. A large number of coherent state basis functions are required to characterize the delocalized features of the phonon wavefunction in the case of large transfer integral, which becomes computationally too demanding for the multi-D ansatz. The MCE approach, on the other hand, uses hundreds to thousands of trajectory guided basis functions and converges very well, thus providing an effective tool for accurate and efficient simulations of polaron dynamics.
我们将多组态 Ehrenfest（MCE）方法扩展到研究一维 Holstein 分子晶体模型的动力学。结果表明，扩展的 MCE 方法与运动方程层次结构方法的基准计算结果完全一致。通过与完全变分多 Davydov D 假设的详细比较，仔细检查了 MCE 方法在描述 Holstein 极化子动力学特性方面的准确性，该模型在广泛的激子转移积分和激子-声子耦合范围内。结果发现，虽然 MCE 方法和多-D 假设对于小的转移积分几乎产生完全相同的结果，但对于大的转移积分，多-D 假设的结果在较长时间后开始偏离 MCE 方法的结果。对于大的转移积分，需要大量的相干态基函数来描述声子波函数的非定域特征，这对于多-D 假设来说计算上要求过高。另一方面，MCE 方法使用数百到数千个轨迹引导基函数，并且收敛得非常好，因此为准确高效地模拟极化子动力学提供了有效工具。
