New Approaches to Path Integral Simulations of Condensed-Phase Quantum Dynamics

南加州大学的麦奇（Chi Mak）获得了理论与计算化学项目的资助，继续他关于凝聚相量子动力学的路径积分模拟的研究。本研究有两个主要目标：1)了解环境对电子转移反应等隧穿系统动力学的影响；2)开发新的仿真技术来实现这一目标。到目前为止，Mak已经开发了两个模型：1)多层阻塞（MLB）算法，它适用于具有多个显式自由度的模型；2)色随机量子动力学（CSQD）方法，它适用于环境由无限简单自由度集合表示的模型。Mak将进一步发展这些想法并将其应用于新系统，同时还将开发一种新的混合方法来处理其他两种方法都无法达到的模型。电子转移反应是一类重要的化学反应，在化学和生物学中具有特殊的相关性。在这些反应中，电子从供体隧穿到受体的能力受到周围环境的严重影响。尽管马库斯理论取得了成功，但许多问题，特别是与电子隧穿动力学的量子特征有关的问题仍然存在。马克的研究将有助于阐明这些重要的贡献，并进一步加深我们对这类重要化学反应的理解。

Chi Mak at the University of Southern California is supported by a grant from the Theoretical and Computational Chemistry Program to continue his research involving path integral simulations of condensed-phase quantum dynamics. The research has two major goals: 1) to understand the influence of the environment on the dynamics of tunneling systems such as those in electron transfer reactions; and 2) to develop new simulation techniques to accomplish this goal. Two models have thus far been developed by Mak: 1) a multilevel blocking (MLB) algorithm which works with models having several explicit degrees of freedom, and 2) a chromostochastic quantum dynamics (CSQD) method that works with models in which the environment is represented by an infinite collection of simple degrees of freedom. Mak will further develop these ideas and apply them to new systems, and also develop a new hybrid method to treat models outside the reach of either of the other two methods.Electron transfer reactions are an important class of chemical reactions with particular relevance in chemistry and biology. In these reactions the electron's ability to tunnel from the donor to the acceptor is heavily influenced by its surroundings. Despite the success of Marcus theory, many questions, especially those related to the quantal features of electron tunneling dynamics, still remain. Mak's research will help to elucidate these important contributions, and further our understanding of this important class of chemical reactions.