Novel Applications of Mixed Quantum-Classical Dynamics to Studies of Charge and Energy Transfer in Chemical and Biological Systems

质子、电子和能量的传输在许多化学和生物现象中发挥着重要作用，如氢键、酶催化、光化学和光合作用，以及在能量转换装置中，如电化学和光伏电池。对这些输运过程的基本理解可以通过对基本分子动力学的理论研究和对经历这些过程的系统的超快光谱测量来实现。需要量子力学来解释质子/电子的动力学和能量再分配。因此，为模拟这些过程所做的任何努力都应该考虑到它们固有的量子力学性质。不幸的是，在当今速度最快的计算机上，无法对这些过程进行全量子力学模拟，这些过程发生在包含大量原子的液体、蛋白质、聚合物和分子组件等环境中。为了显著降低计算成本，在这些情况下，人们可以用量子力学来处理与传输直接相关的少量粒子，而其余的粒子可以使用经典牛顿力学来处理，以达到良好的近似值。我们的目标是应用这种混合的量子-经典方法来模拟具有基础和技术意义的化学和生物系统中各种电荷和能量转移过程的动力学和超快光谱(即光致电子转移、质子耦合电子转移和振动能量转移)，从而为控制它们以提高太阳能收集材料、水分解和太阳能燃料生产的催化剂以及分子电子学应用的效率和效率提供新的线索。我们将专注于控制方法，这些方法依赖于改变系统经典部分的属性，或者将量子部分耦合到属性可以很容易调节的光场。这些研究的结果最终将导致设计设备的原则，这些设备可以减少加拿大对化石燃料的依赖，或者用于加拿大的电子工业。

The transport of protons, electrons, and energy plays an instrumental role in many chemical and biological phenomena such as hydrogen bonding, enzyme catalysis, photochemistry, and photosynthesis, and in energy conversion devices such as electrochemical and photovoltaic cells. A fundamental understanding of these transport processes may be achieved through theoretical studies of the underlying molecular dynamics and ultrafast spectroscopic measurements of systems undergoing these processes. Quantum mechanics is required for explaining the dynamics of protons/electrons and energy redistribution. Therefore, any efforts made towards modeling these processes should account for their inherently quantum mechanical nature. Unfortunately, fully quantum mechanical simulations of these processes occurring in environments such as liquids, proteins, polymers, and molecular assemblies, which contain large numbers of atoms, are not possible on today’s fastest computers. To dramatically cut down the computational costs, in these cases, one can treat a small number of particles directly associated with the transport quantum mechanically, while the remaining particles can be treated using classical Newtonian mechanics to a good approximation. Our goal is to apply such mixed quantum-classical approaches for simulating the dynamics and ultrafast spectra of a variety of charge and energy transfer processes in chemical and biological systems of fundamental and technological importance (i.e. photo-induced electron transfer, proton-coupled electron transfer, and vibrational energy transport), and thereby shed new light on ways of controlling them to increase the efficiency and efficacy of solar energy harvesting materials, catalysts for water splitting and solar fuels production, and molecular electronics applications. We will focus on control methods, which rely on varying the properties of the classical part of the system, or coupling the quantum part to light fields whose properties can be easily tuned. The results of these studies will ultimately lead to principles for designing devices that can reduce Canada's dependence on fossil fuels or be used in Canada’s electronics industry.