Methods for Simulating Nonadiabatic Dynamics with Trajectories

加州大学欧文分校的Craig C. Martens获得了化学系化学理论、模型和计算方法项目的奖励，开发了模拟分子系统量子过程的计算方法。普通的牛顿力学或经典力学被用来理解日常物体的运动，比如高尔夫球或飞机。然而，像电子这样的非常轻的粒子必须用量子力学来描述。伴随化学反应的原子和电子的运动落在了物质的经典力学描述和量子力学描述的边界上。马滕斯和他的研究小组通过将量子效应纳入概念直观和计算效率高的经典力学框架来探索这一前沿。他们专注于分子的非绝热动力学，其中量子电子跃迁伴随着几乎经典的振动和组成原子的化学重排。马滕斯的目标是在基本层面上理解量子力学的本质，同时开发出比现有方法更有效、更准确的方法。他们的研究活动与一个拓展项目并行，包括指导本科生和高中生编写教育电脑游戏，将量子效应添加到熟悉但固有的经典游戏玩法中，以一种非科学家甚至儿童都能理解的方式说明量子力学。马滕斯和他的团队正在开发一种新的随机表面跳变方法，在经典轨迹背景下完全准确地捕获量子非定域性和相干性。与目前的方法不同，这种新方法描述了系统的量子特性，如种群、相干性和能量的分配，这些特性是通过作为一个整体的系综轨迹之间的相互关系来共同描述的。Martens及其同事的目标是实现一种定量准确的基于轨迹的方法，用于在此框架内模拟带有电子跃迁的分子动力学，这既是一项基本成就，也是引入进一步近似的基准。最终，他们寻求基于充分理解和经过测试的妥协而不是临时简化的准确但经济和有效的方法。他们正在构建一种独立的轨迹方法，结合严格推导的量子广义力，避免了标准方法的特殊特征，目标是更广泛的适用性，同时成本大致相等。Martens小组正在寻求扩展到多维系统，其中能量分配和几何相位效应为新方法提供了具有挑战性的测试。此外，马滕斯正在实施一项外展计划，弥合表演艺术与科学之间的差距，目标是提高科学作为一种职业的形象和可及性。他还指导本科生和高中生开发电子游戏，向年轻人和非科学家讲解量子力学的基本原理。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Craig C. Martens of the University of California, Irvine is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop computational methods to simulate quantum processes in molecular systems. Ordinary Newtonian or classical mechanics is used to understand the motion of everyday objects such as golf balls or airplanes. Very light particles such as electrons, however, must be described using quantum mechanics. The motion of atoms and electrons that accompany chemical reactions falls in the frontier separating classical and quantum mechanical descriptions of matter. Martens and his research group explore this frontier by incorporating quantum effects into the conceptually intuitive and computationally efficient framework of classical mechanics. They focus on nonadiabatic dynamics of molecules, where quantum electronic transitions accompany the nearly classical vibrations and chemical rearrangements of the constituent atoms. Martens' goal is to gain an understanding of the nature of quantum mechanics at a fundamental level while at the same time developing methods that are more efficient and accurate than existing approaches. Their research activities are paralleled by an outreach program that includes mentoring undergraduate and high school students to write educational computer games that add quantum effects to familiar but inherently classical gameplay to illustrate quantum mechanics in a manner that is accessible to nonscientists, and even to children. Martens and his group are developing a new stochastic surface hopping approach that captures quantum nonlocality and coherence fully and accurately in a classical trajectory context. Unlike current methodology, the novel approach describes quantum properties of the system such as the populations, coherence, and the partitioning of energy collectively through interrelationships between the trajectories of the ensemble taken as a whole. Martens and coworkers aim to achieve a quantitatively accurate trajectory-based method for simulating molecular dynamics with electronic transitions within this framework, both as a fundamental achievement and as a benchmark for the introduction of further approximations. Ultimately, they seek accurate but economical and efficient methodologies based on well-understood and tested compromises rather than ad hoc simplifications. They are constructing an independent trajectory approach incorporating rigorously derived quantum generalized forces that avoid ad hoc features of standard methodology with the goal of broader applicability while being roughly equal in cost. The Martens group is pursuing extensions to multidimensional systems, where energy partitioning and geometric phase effects provide challenging tests of the new approach. In addition, Martens is implementing an outreach program that bridges the gap between performing arts and science, with the goals of enhancing the image and accessibility of science as a career. He is also mentoring undergraduate and high school students in the development of video games that illustrate the fundamentals of quantum mechanics to youth and nonscientists.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.