School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
J Chem Phys. 2012 Jun 7;136(21):214101. doi: 10.1063/1.4723669.
In many physical, chemical, and biological systems energy and charge transfer processes are of utmost importance. To determine the influence of the environment on these transport processes, equilibrium molecular dynamics simulations become more and more popular. From these simulations, one usually determines the thermal fluctuations of certain energy gaps, which are then either used to perform ensemble-averaged wave packet simulations, also called Ehrenfest dynamics, or to employ a density matrix approach via spectral densities. These two approaches are analyzed through energy gap fluctuations that are generated to correspond to a predetermined spectral density. Subsequently, density matrix and wave packet simulations are compared through population dynamics and absorption spectra for different parameter regimes. Furthermore, a previously proposed approach to enforce the correct long-time behavior in the wave packet simulations is probed and an improvement is proposed.
在许多物理、化学和生物系统中，能量和电荷转移过程至关重要。为了确定环境对这些传输过程的影响，平衡分子动力学模拟变得越来越流行。通常，从这些模拟中确定某些能量间隙的热涨落，然后要么使用这些能量间隙来执行系综平均波包模拟，也称为 Ehrenfest 动力学，要么通过光谱密度使用密度矩阵方法。通过生成与预定光谱密度相对应的能隙波动来分析这两种方法。随后，通过不同参数区域的种群动力学和吸收光谱对密度矩阵和波包模拟进行比较。此外，还探讨了一种先前提出的方法，以在波包模拟中强制实现正确的长时间行为，并提出了改进。
