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

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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.