Exploring the Connections between the Nonlinear Spectroscopy and the Potential Energy Landscapes of Liquids

在一个由化学系化学理论、模型和计算方法项目资助的项目中，布朗大学的理查德·斯特拉特教授正在开发新的方法来理解液体中分子表现出的复杂和看似不稳定的运动模式。眼下的目标是深入了解玻璃形成液体和液晶的行为。这两种材料都具有巨大的技术意义，因为它们与非晶态材料的制造和实用的显示设备相关。此外，这些方法具有潜在的应用范围，可以跨越更广泛的溶液中的化学问题。其基本思想是利用高性能计算的最新进展来绘制最有利的分子路径。与斯特拉特教授和他的研究小组正在设计的分析方法相结合，其他使用超快激光技术的科学小组可以寻找这些所需的运动模式。推动这一努力的动力是，现在有可能通过过冷和介生液体等复杂系统的真实势能景观找到测地线(最有效的)路线。但是，随着发现这些路径可以通过计算询问来辨别分子机制，就有可能设计多维光谱学实验来确定这些机制。斯特拉特小组将研究各种测地线定义的分子机制的特定非线性光谱特征，看看适当选择的光谱是否有助于解开目前围绕过冷易碎液体和液晶动力学的一些谜团。这一努力的一个组成部分(以及其更广泛影响的一部分)将是利用这个项目作为一种工具，让大学生接触到一线以计算为导向的研究中面临的问题。美国有一个受过教育的公民，并且懂得如何使用计算机模拟等21世纪的科学方法来解决具有挑战性的问题，这一点的重要性怎么估计都不为过。通过将重点放在项目中精心挑选的部分，来自各种不同背景的本科生将能够欣赏科学研究提供的挑战和可能性。

In a project funded by the Chemical Theory, Models, and Computational Methods program of the Chemistry Division, Professor Richard Stratt of Brown University is developing new ways of understanding the complex and seemingly erratic patterns of motion exhibited by molecules in liquids. The immediate goal is to gain insights into the behavior of glass-forming liquids, and liquid crystals. Both of these materials are of enormous technological significance because of their relevance to the manufacture of amorphous materials and to practical display devices. In addition, these methods have potential applications to span an even broader range of chemical problems in solutions. The basic idea is to take advantage of recent progress in using high-performance computation to map out the most favorable molecular pathways. In combination with analysis methods being devised by Professor Stratt and his research group, other scientific groups using ultrafast laser techniques can look for these desired patterns of motion.The engine driving this effort is that it is now possible to find the geodesic (most efficient) routes through realistic potential energy landscapes of such complex systems as supercooled and mesogenic liquids. But, with the discovery that these routes can be computationally interrogated to discern molecular mechanisms comes the possibility of designing multidimensional spectroscopy experiments to ascertain those mechanisms. The Stratt group will be investigating the specific nonlinear spectroscopic signatures of various kinds of geodesic-defined molecular mechanisms to see if properly chosen spectra can help resolve some of the current mysteries surrounding the dynamics of supercooled fragile liquids and liquid crystals. An integral part of this effort (and part of its broader impact) will be the use of this project as a vehicle for exposing college undergraduates to issues faced in frontline computationally-oriented research. It is hard to overestimate the importance of the United States having an educated citizenry with an appreciation of how such 21st-century scientific methods as computer simulation can be used to approach challenging problems. By focusing on carefully selected portions of the project, undergraduates from a wide variety of different background will be able to gain an appreciation of the challenges and possibilities provided by scientific research.