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

在一个由化学学部化学理论、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分子所表现出的复杂的、看似不稳定的运动模式。目前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，因为它们与非晶材料的制造和实际显示设备有关。此外，这些方法在解决更广泛的化学问题方面具有潜在的应用前景。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途径。结合Stratt教授和他的研究小组设计的分析方法，其他科学小组使用超快激光技术可以寻找这些所需的运动模式。推动这一努力的动力是，现在有可能通过像过冷和介生液体这样复杂系统的现实势能景观找到测地线（最有效的）路线。但是，随着这些路径可以通过计算来辨别分子机制的发现，设计多维光谱实验来确定这些机制成为可能。Stratt小组将研究各种测地定义的分子机制的特定非线性光谱特征，看看正确选择的光谱是否有助于解决目前围绕过冷脆弱液体和液晶动力学的一些谜团。这项工作的一个组成部分（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，让大学本科生接触到前沿计算导向研究面临的问题。美国有一批受过良好教育的公民，他们懂得如何利用计算机模拟等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。通过专注于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对科学研究提供的挑战和可能性有所了解。

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.