Simulation and Theory of Crystal-Melt Interfaces

Brian Laird博士得到了理论和计算化学计划的资助，继续他对晶体-熔体界面的模拟和理论的研究。Laird之前在这一领域的工作主要集中在理想硬球系统的固液界面上。建议的继续将这项工作扩展到更现实的系统，如金属和金属合金以及具有取向依赖相互作用的系统。密度泛函理论结合形式统计力学将用于：1)计算界面自由能；2)预测金属合金等混合物界面处的溶质偏析；3)预测分子体系固液界面的结构和动力学。由于这一研究领域明显缺乏实验数据，因此模拟将提供“实验”数据，用于评估和开发此类系统的分析理论。为了充分了解诸如晶体生长、均匀成核、平衡晶体形状或平衡溶质偏析等技术上重要的现象，有必要掌握晶体及其熔体之间界面微观性质的详细信息。不幸的是，几乎完全缺乏关于这些系统的实验数据，这使得这些研究变得困难。因此，计算方法，如Laird提出的计算机模拟技术，远远超出了它们在解释实验数据方面的通常作用，成为为这些重要过程建立分析理论的重要数据。

Dr. Brian Laird is supported by a grant from the Theoretical and Computational Chemistry Program to continue his research on the simulation and theory of crystal-melt interfaces. Laird's prior work in this area has been focused on the solid-liquid interface for idealized hard sphere systems. The proposed continuation will extend this work to more realistic systems such as metals and metal alloys and to systems with orientationally dependent interactions. Density-functional theory in conjunction with formal statistical mechanics will be used to: 1) calculate the interfacial free energy; 2) predict the solute segregation at the interface for mixtures such as metal alloys; and 3) predict the structure and dynamics for solid-liquid interfaces of molecular systems. Since there is a significant lack of experimental data in this area of research, the simulations will provide "experimental" data with which to evaluate and develop analytical theories for such systems.In order to fully understand such technologically important phenomena as crystal growth, homogeneous nucleation, equilibrium crystal shapes or equilibrium solute segregation, it is necessary to have detailed information on the microscopic properties of the interface between a crystal an its melt. Unfortunately, there is nearly a total lack of experimental data on such systems making these studies difficult. Thus, computational methods such as the computer simulation techniques proposed by Laird go far beyond their usual roles in the interpretation of experimental data and become important data upon which to base analytical theories for these important processes.