Development of next generation quantum master equation and generalized master equation approaches

纽约州立大学皇后学院的Seogjoo Jang得到了化学系化学理论、模型和计算方法项目的支持，开发了新的量子主方程(QME)和广义主方程(GME)，可以将分子水平的量子动力学与更长的长度和更长的时间尺度动力学联系起来。这是通过将最近开发的极化子QME(PQME)扩展到更广泛的参数范围，并通过开发新的粗粒度QME/GME方法来实现的，这些方法可以将小长度尺度上的高精度计算结合到大长度尺度上的高效计算中。这项研究的另一个目标是提高QME/GME方法的可靠性和能力。Jang和他的同事们还在开发一种新的QME，它可以直接利用绝热电子态及其导数耦合的信息。原子分子动力学模拟正在被用于检验和修改紫色细菌的光合光采集复合体2(LH2)的激子浴哈密顿量的传统形式。在这项研究中发展的方法，量子和广义主方程方法，为研究复杂分子环境中的激子和电荷载流子动力学提供了自然的框架，如自然捕光络合物和有机光伏器件。Jang和他的研究小组正在将这些方法提升到一个新的水平，这样它们就可以以更准确和现实的方式应用，而不需要依赖简单的模型系统。这一结果--对大范围长度/时间范围内的量子弛豫和输运动力学的统一和可靠的描述--将有助于阐明隐藏在复杂分子系统中大规模激子和电荷输运动力学的纯经典行为中的量子效应。

Seogjoo Jang of CUNY Queens College is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry division to develop new classes of quantum master equation (QME) and generalized master equation (GME) that can bridge molecular level quantum dynamics with larger length and longer time scale dynamics. This is achieved by extending the recently developed polaronic QME (PQME) for a broader regime of parameters, and by developing new coarse-grained QME/GME approaches that can incorporate highly accurate calculation at small length scales into efficient calculation for larger length scales. Another objective of the research is to enhance the reliability and capability of QME/GME approaches. Jang and his coworkers are also developing a new kind of QME that can utilize information on adiabatic electronic states and their derivative couplings directly. Atomistic molecular dynamics simulations are being conducted to examine and modify the conventional form of the exciton-bath Hamiltonian for the photosynthetic light harvesting complex 2 (LH2) of purple bacteria. The methods developed in this research, quantum and generalized master equation approaches, offer natural frameworks for studying exciton and charge carrier dynamics in complex molecular environments, such as natural light harvesting complexes and organic photovoltaic devices. Jang and his research group are taking these approaches to a new level so that they can be applied in a more accurate and realistic manner without relying on simple model systems. The result -- unified and reliable descriptions of quantum relaxation and transport dynamics across a wide range of length/time -- will help elucidate the quantum effects hidden in what appears to be the purely classical behavior of large scale exciton and charge transport dynamics in complex molecular systems.