Collaborative Research: CDS&E: Experimentally verified nano-oxidation simulations of Cu surfaces

关于宏观尺度上的金属表面氧化有大量的知识，但关于该过程如何在最小分子尺度上开始的知之甚少。 理解在这种纳米（十亿分之一米的大小）长度尺度上发生的氧化现象具有科学和技术的重要性，因为越来越多的材料在纳米尺度上被工程化用于实际应用。 这种纳米级材料的稳定性不一定能直接从它们的大块对应物的知识中推断出来，需要新的理论来预测这种小尺度下的材料特性。 这个合作项目汇集了一个理论化学家谁将模拟铜表面的氧化，理论物理学家谁将联合收割机这些机制在氧化物生长动力学的统计模型，最后一个实验显微镜谁可以观看纳米尺度的氧化物岛的生长与电子显微镜的个人反应机制。 该研究团队将共同努力，从原子尺度上了解铜表面的初始氧化。 作为这项工作的一部分，将开发新的模拟方法。将开发和用于模拟氧化的软件将免费向其他研究人员和公众发布。 这些技术也将被纳入研究生课程，并作为德克萨斯州奥斯汀和宾夕法尼亚州匹兹堡高中外展计划的一部分。 该奖项支持匹兹堡大学和德克萨斯大学奥斯汀分校之间的合作研究和教育工作，以开发可用于模拟纳米氧化的材料计算工具，并将计算预测与实验观察相关联。PI将集成用于模拟表面动力学的通用代码，并解决拟议研究中的三个关键挑战，即（i）使用加速动力学方法和非格子自适应动力学蒙特卡罗（KMC）与经验势和密度泛函理论来提取表面氧化的反应机制，（ii）继续开发薄膜氧化KMC方法，特别是采取它从2到3维，和（iii）开发一种方法，用于粗粒化的反应机制的表示发现与自适应KMC提供的事件表的三维薄膜氧化代码。这些研究将为薄膜氧化模拟提供现实的输入参数，允许对成核行为、纳米氧化和聚结过程中氧化物岛的形态演变进行关键性的洞察，并提供理解岛稳定性所需的表面和界面能。这种合作建立在现有的基础设施上，包括匹兹堡的实验电子显微镜工作以及奥斯汀和匹兹堡的理论和软件工作。 这个研究小组将共同努力，从原子尺度上和更高层次上了解铜表面的初始氧化。 用于模拟氧化的软件将免费向其他研究人员和公众发布。 这些技术也将被纳入研究生课程，并作为奥斯汀和匹兹堡高中外展计划的一部分。

NON-TECHNICAL SUMMARYThere is a great deal of knowledge about the oxidation of metal surfaces on macroscopic scales, but very little is known about how the process starts at the smallest molecular scales. Understanding the oxidation phenomena that occur at such nanometer (one billionth the size of a meter) length scales is of both scientific and technological importance, since more and more materials are being engineered at nanometer scales for practical applications. The stability of such nanoscale materials cannot necessarily be inferred directly from the knowledge about their bulk counterparts, and new theories are needed to predict material properties at such small scales. This collaborative project brings together a theoretical chemist who will model the individual reaction mechanisms of the oxidation of a copper surface, a theoretical physicist who will combine these mechanisms in a statistical model of the oxide growth kinetics, and finally an experimental microscopist who can watch the growth of nanometer scale oxide islands with an electron microscope. This research team will work together to understand the initial oxidation of a copper surface, from the atomic scale on and up. New simulation methodologies will be developed as part of this effort. The software that will be developed and used to model the oxidation will be released freely to other researchers and to the public. The techniques will also be incorporated into graduate-level courses and as part of high-school outreach programs both in Austin, TX and Pittsburgh, PA. TECHNICAL SUMMARY This award supports a collaborative research and education effort between the University of Pittsburgh and the University of Texas at Austin for developing materials computational tools that can be used to model nano-oxidation, and to correlate computational predictions with experimental observations. The PIs will integrate versatile codes for modeling dynamics at surfaces and address three key challenges in the proposed research, which are (i) to use accelerated dynamics methods and off-lattice adaptive kinetic Monte Carlo (KMC) with empirical potentials and density functional theory to extract the reaction mechanisms of surface oxidation, (ii) to continue the development of the Thin Film Oxidation KMC approach, particularly taking it from 2 to 3 dimensions, and (iii) to develop a method for coarse graining the representations of reaction mechanisms found with adaptive KMC to provide the event tables for the three-dimensional Thin Film Oxidation code. These studies will provide realistic input parameters for the Thin Film Oxidation simulations, allow for critical insights to be made into the nucleation behavior, morphological evolution of oxide islands during nano-oxidation and coalescence, and provide the surface and interface energies required to understand island stability. This collaboration builds on existing infrastructure, including the experimental electron microscopy effort in Pittsburgh and the theoretical and software efforts in Austin and Pittsburgh. This research team will work together to understand the initial oxidation of copper surface, from the atomic scale on and up. The software that will be used to model the oxidation will be released freely to other researchers and to the public. The techniques will also be incorporated into graduate-level courses and as part of high-school outreach programs both in Austin and Pittsburgh.