Theoretical Studies of Etching and Growth Dynamics at Surfaces

在理论和计算化学项目的资助下，加里森博士将通过分子动力学模拟来研究气体与固体表面的反应，以获得对所涉及的原子运动的微观和基本理解。重点将放在涉及固体本身的生长或破坏（蚀刻）的反应上。从用于确定表面结构的能量和角度分布到在大型生物分子被轰击时喷射过程中观察到的碎片模式，解释实验数据需要对这一过程有一个基本的理解。然而，为了真实地模拟这些过程，首先有必要统一这些系统的多体相互作用势或力场的描述。因此，加里森博士和她的学生将通过研究特定的铑表面来解决这个问题。在过去的几十年里，实验学家和理论家一直在寻找晶体表面化学反应过程中原子的微观运动与反应速率等宏观可观察到的现象之间的关系。这种关系的发展对每个研究团体来说都是困难的。在表面上进行定义明确的实验的技术直到最近才趋于完善。研究详细反应机理的理论方法依赖于可靠的多体相互作用势的可用性。从头算方法可以成功地应用于定义少量原子和原子之间的相互作用，但对于大量原子的集合来说，这种方法变得繁琐和计算上令人望而却步。加里森博士希望发展新的理论方法，可以应用于描述发生在固体表面的化学反应，重点是那些涉及固体本身生长或破坏的过程。

With support from this grant in the Theoretical and Computational Chemistry program, Dr. Garrison will investigate, via molecular dynamics simulations, the reactions of gases with solid surfaces in order to gain a microscopic and fundamental understanding of the atomic motions involved. Emphasis will be placed on reactions that involve either the growth or destruction (etching) of the solid itself. A fundamental understanding of this process is needed for the interpretation of experimental data ranging from the energy and angular distributions used in determining surface structures to the fragmentation patterns observed in the ejection process when large biomolecules are bombarded. To realistically model these processes, however, it will first be necessary to unify the description of the many-body interaction potentials or force fields for these systems. Hence, Dr. Garrison and her students will work on this problem by studing specific rhodium surfaces. The relationship between the microscopic motion of atoms during chemical reactions at crystal surfaces and macroscopic observables such as reaction rates has been sought by experimentalists and theoreticians alike for the last several decades. The development of such a relationship has been difficult for each research community. Techniques for performing well-defined experiments at surfaces are only recently being perfected. Theoretical methods for examining detailed reaction mechanisms are dependent upon the availability of reliable manybody interaction potentials. Ab initio methods which can be successfully applied to define and the interaction between small numbers of atoms become cumbersome and computationally prohibitive for large ensembles of atoms. Dr. Garrison expects to develop new theoretical approaches which may be applied to describing chemical reactions which occur at solid surfaces with an emphasis on those processes that involve either the growth or destruction of the solid itself.