Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, Massachusetts 02138, USA.
J Chem Phys. 2012 Dec 14;137(22):22A547. doi: 10.1063/1.4762441.
In this work, we develop an approach to treat correlated many-electron dynamics, dressed by the presence of a finite-temperature harmonic bath. Our theory combines a small polaron transformation with the second-order time-convolutionless master equation and includes both electronic and system-bath correlations on equal footing. Our theory is based on the ab initio Hamiltonian, and is thus well-defined apart from any phenomenological choice of basis states or electronic system-bath coupling model. The equation-of-motion for the density matrix we derive includes non-markovian and non-perturbative bath effects and can be used to simulate environmentally broadened electronic spectra and dissipative dynamics, which are subjects of recent interest. The theory also goes beyond the adiabatic Born-Oppenheimer approximation, but with computational cost scaling such as the Born-Oppenheimer approach. Example propagations with a developmental code are performed, demonstrating the treatment of electron-correlation in absorption spectra, vibronic structure, and decay in an open system. An untransformed version of the theory is also presented to treat more general baths and larger systems.
在这项工作中，我们开发了一种处理相关多电子动力学的方法，该方法由有限温度谐波浴的存在来修饰。我们的理论将小极化子变换与二阶无时变主方程相结合，并平等地包含电子和系统-浴相关。我们的理论基于从头算哈密顿量，因此除了任何基于基态或电子系统-浴耦合模型的经验选择之外，它都有明确定义。我们推导出的密度矩阵运动方程包括非马尔可夫和非微扰浴效应，可以用于模拟环境增宽的电子光谱和耗散动力学，这是最近的研究课题。该理论还超越了绝热 Born-Oppenheimer 近似，但计算成本与 Born-Oppenheimer 方法一样呈线性增长。通过发展中的代码进行了示例传播，演示了在开放系统中吸收光谱、振子结构和衰减中电子相关的处理。还提出了该理论的未经变换版本，以处理更一般的浴和更大的系统。
