Theory of Fluids, Phase Transitions, and Interfaces

Benjamin Widom得到了理论和计算化学项目的资助，继续他在流体、相变和界面理论方面的工作。提出了三个具体研究领域的工作。在第一个研究领域，将研究界面结构和界面相变，以努力了解均匀流体相之间非均匀接触区域的性质。在这些研究中，将使用一个理论模型，它应该阐明两种可供选择的、有时是不一致的观点之间的联系，并解决差异，即自由能泛函理论和界面位移理论。第二个研究领域涉及周期性调制（液晶）相的共存，以及这些相之间界面的结构和热力学。一项理论研究将追踪各向同性流体中散射峰的演化，其中有一个初始周期性，当流体经历二阶跃迁到有序的液晶状态时，散射峰变成一个真正的δ函数布拉格峰。第三个研究领域涉及使用缩放理论来开发带电长链聚合物的电泳模型。所提出的研究将阐明聚合物链长与外加电场之间的相互作用。在日常生活中，流体相之间的界面无处不在，但对于界面结构的细节或界面上发生的过程却知之甚少。Widom的工作将为这些接触区域的空间结构和热力学提供分子水平的见解。

Benjamin Widom is supported by a grant from the Theoretical and Computational Chemistry Program to continue his work on the theory of fluids, phase transitions and interfaces. Work is proposed in three specific areas of research. In the first area of study, interfacial structure and interfacial phase transitions will be studied in an effort to understand the nature of the inhomogeneous region of contact between otherwise homogeneous fluid phases. In these studies a theoretical model will be used which should illuminate the connection, and resolve the differences, between two alternative and sometimes discrepant points of view, that of free energy functional theory and that of an interface displacement theory. The second area of study involves the coexistence of periodically modulated (liquid crystal) phases, and the structure and thermodynamics of the interface between such phases. A theoretical study will trace the evolution of the scattering peak in the isotropic fluid in which there is an incipient periodicity into a true delta function Bragg peak as the fluid undergoes a second order transition to an ordered, liquid-crystalline state. The third area of research involves the use of scaling theory to develop a model for the electrophoresis of charged, long-chain polymers. The proposed study will elucidate the interplay between the chain length of the polymer and the applied electric field. In the everyday world, interfaces between fluid phases are ubiquitous, yet very little is known about the details of the structure of the interface or the processes which are going on at the interface. Widom's work will provide molecular level insights on the spatial structure and thermodynamics of those contact regions.