Phase Transitions in Nanosystems: Effects of Surface, Importance of Fluctuations.

教授霍华德赖斯是由理论和计算化学计划的支持，在纳米系统进行相变的研究。 特别强调的是表面效应和波动的作用。理论工具包括热力学、统计力学和密度泛函理论。 对于技术上感兴趣的系统，准确的分子水平的知识和/或分子间的潜力是不可用的，一个增强的液滴模型的开发和应用。 这种方法依赖于可测量的宏观热物理量，如表面张力，密度和蒸汽压。正在考虑的问题领域包括集群成核过程，相变集群，大气气溶胶，流体局限于纳米孔，和毛细管冷凝的流体。成核是所有科学技术中最普遍存在的现象之一。 尽管成核理论很重要，但直到最近它还是唯象的。 一个连贯的，一致的分子成核理论的制定在大气科学和纳米多孔和介孔材料的许多实际应用具有重要的影响。 就前者而言，云滴的凝固与高层大气中的臭氧消耗有关。关于后者，纳米和介孔系统用于各种工业过程，例如化学分离和螯合、吸收材料、催化和油回收。 随着分子筛和纳米管合成的进一步发展，对表面效应的更全面的理解将是必要的。 研究生和博士后培训是在音乐会上完成的研究

Professor Howard Reiss is supported by the Theoretical and Computational Chemistry Program to perform research on phase transitions in nanoscale systems. Particular emphasis is on surface effects and on the role of fluctuations. Theoretical tools include thermodynamics, statistical mechanics and density-functional theory. For technologically interesting systems where accurate molecular-level knowledge and/or intermolecular potentials are unavailable, an enhanced liquid-drop model is developed and applied. This method relies on measurable macroscopic thermophysical quantities such as surface tension, density and vapor pressures. Problem areas under consideration include cluster nucleation processes, phase transitions in clusters, atmospheric aerosols, fluids confined to nanopores, and capillary condensation of fluids. Nucleation is one of the most ubiquitous phenomena in all of science and technology. Despite its importance, the theory of nucleation has until recently been phenomenological. The formulation of a coherent, consistent theory of molecular nucleation has important consequences for many practical applications in atmospheric science and in nanoporous and mesoporous materials. With respect to the former, solidification of cloud droplets is relevant to ozone depletion in the upper atmosphere. With respect to the latter, nano- and meso- porous systems are used in a variety of industrial processes such as chemical separation and sequestration, absorbent materials, catalysis and oil recovery. As further progress is made in synthesis of molecular sieves and nanotubes a more complete understanding of surface effects will be necessary. Graduate and postdoctoral training is accomplished in concert with the research