Bridging Time Scales with a Unit Process Approach for Modeling Ion Interactions with Materials

桥接时间尺度与一个单元过程的方法建模离子与材料的相互作用在这个程序中，一个新的方法将开发用于建模多时间尺度的问题，在离子与材料的相互作用的应用。 我们称之为一个单元过程的方法，原子建模方法被用来提取在短时间尺度上的单个事件的平均影响，然后将数据纳入长时间尺度模型的更大和更慢的系统演化。 该方法将通过两个具体的任务，在离子与材料的相互作用的一类问题。 首先，离子轰击的基本单元过程模型将更加定量;在初步工作中展示的两个例子是用于轰击非晶表面的弹坑函数方法和用于轰击结晶表面的缺陷统计方法。 第二，这些改进的单元过程模型将被纳入两种类型的长时间尺度系统形态学研究，即（i）经历离子粗糙化和扩散平滑化的离子轰击非晶表面的基于坑函数的表面演化研究，和（ii）离子轰击结晶表面形态学的浓度演化方程研究，其中，离子诱导缺陷浓度的统计布居演变为主导表面结构。新方法将引入一个强大的框架，用于桥接力学建模中的多个时间尺度，使跨越从飞秒到数小时的时间尺度的精确力学模型成为可能。 它还将导致对离子与半导体相互作用的理解取得重大进展，这将影响离子注入，表面改性和铣削领域，以及航空航天和能源应用的辐射损伤。 该计划也将在UIUC和超越重要的教育影响。 在该计划的第一年，PI将帮助建立工程科学（SES）在UIUC的社会的学生章，并将利用2008年SES会议，正在UIUC举行，以帮助成长的章节。 学生章将从机械工程和工程力学的本科生和研究生中抽取成员。

Bridging Time Scales with a Unit-Process Approach for Modeling Ion Interactions with MaterialsIn this program a new approach will be developed for modeling multi-timescale problems with applications in ion interactions with materials. We refer to this as a unit-process approach, whereby atomistic modeling methods are used to extract the average effects of single events at the short time scale, and then the data are incorporated in long time scale models for the larger and slower system evolution. The approach will be demonstrated for a class of problems in ion interactions with materials, via two specific tasks. First, basic unit-process models for ion-bombardment will be made more quantitative; the two examples demonstrated in preliminary work are the crater function approach for bombardment of amorphous surfaces, and the defect statistics approach for bombardment of crystalline surfaces. Second, these improved unit-process models will be incorporated into two types of long time scale system morphology studies, namely (i) crater function based surface evolution studies of ion bombarded amorphous surfaces undergoing ion roughening and diffusional smoothing, and (ii) concentration evolution equation studies of ion bombarded crystalline surface morphology, where statistical populations of ion induced defect concentrations evolve to dominate the surface structure.The new approach will introduce a powerful framework for bridging multiple time scales in mechanics modeling, making possible accurate mechanics models spanning time scales from femtoseconds to hours. It will also lead to significant advances in understanding ion interactions with semiconductors, which will impact the fields of ion implantation, surface modification, and milling, as well as radiation damage for aerospace and energy applications. The program will also have important educational impact at UIUC and beyond. During the first year of the program, the PI will help establish a student chapter of the Society of Engineering Science (SES) at UIUC and will leverage the 2008 SES conference, being held at UIUC, to help grow the chapter. The student chapter will draw members from undergraduate and graduate students in both mechanical engineering and engineering mechanics.