Animating Lewis Dots: the development of transferable sub-atomistic force fields for efficient, intuitive, turnkey simulations of chemical reactions

布兰迪斯大学的朱迪思·赫兹菲尔德得到了化学理论、模型和计算方法项目的支持，该项目旨在为分子模拟开发反应力场。她的目标是使理论与实验成为探索和理解复杂化学反应途径的更灵活的合作伙伴。理想情况下，计算化学应该是准确的、通用的、高效的和用户友好的。这是一项艰巨的任务，因此计算化学通常只优先考虑其中的几个目标。赫兹菲尔德和他的同事们正在开发一种新的方法，寻求将准确的多功能性与效率和用户友好性结合起来。这项工作有望为研究人员提供有用的计算工具，以模拟在广泛的现实溶剂中的化学反应。这项研究可能会对催化和先进制造产生影响。该项目还为教育工作者提供了可视化工具，这些工具有助于指导学生了解化学反应的机理。思考和交流反应的最便捷工具是半经典的“刘易斯点”图。这个有百年历史的规则是“经典”的，因为价电子和核是独立可移动的粒子，而“半”是指这些粒子遵循非经典规则。赫兹菲尔德的工作试图通过为刘易斯的亚原子粒子开发力场，有效和高效地结合量子效应，来提供迄今为止定性图像的量化版本。这个项目建立在他们早期在非金属的酸碱化学(具有成对的价电子)以及非金属和金属的电离和自旋态(具有单独的价电子模型)方面的工作的基础上。特别是，研究人员正在使用更好的理解交换对能量的贡献，以扩大适用范围。这项工作包括训练、验证和演示描述粒子之间相互作用的潜力。这个奖项反映了NSF的法定使命，通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为是值得支持的。

Judith Herzfeld of Brandeis University is supported by an award from the Chemical Theory, Models and Computational Methods program to develop reactive force fields for molecular simulation. Her goal is to make theory a nimbler partner with experiment in exploring and understanding the pathways of complex chemical reactions. Ideally, computational chemistry should be accurate, versatile, efficient and user-friendly. This is a tall order so computational chemistry usually prioritizes only a couple of these goals. Herzfeld and coworkers are developing a new approach that seeks to combine accurate versatility with efficiency and user-friendliness. This work is expected to provide researchers with useful computational tools for simulating chemical reactions in a broad range of realistic solvents. This research may have impacts in catalysis and advanced manufacturing. The project also provides educators with visualization tools that are useful for instructing students in the mechanisms of chemical reactions. The handiest tool for thinking and communicating about reactions has been the semi-classical "Lewis dot" picture. This century old rubric is "classical" in the sense of thinking of valence electrons and kernels as independently mobile particles, and "semi" in the sense that these particles follow non-classical rules. Herzfeld's work seeks to provide a quantitative version of this heretofore qualitative picture by developing force fields for Lewis' sub-atomistic particles that effectively and efficiently incorporate quantum effects. This project builds on their earlier work on the acid-base chemistry of non-metals (with paired valence electrons) and the ionization and spin states of nonmetals and metals (with valence electrons modeled singly). In particular, the researchers are using an improved understanding of the exchange contributions to the energy to extend the range of applicability. The work involves training, validating and demonstrating the potentials that describe the interactions between the particles. The goal is for these simulations be "turn-key" in the sense of requiring no input as to reaction intermediates or products.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.