CAREER: Nanomechanics from First principles: A Symmetry-Adapted Methodology

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This Faculty Early Development Program (CAREER) grant provides funding for developing a novel multiscale methodology that will derive practical continuum models for nano-objects directly from their first-principles atomistic description. The nanomechanical atomistic computations needed for building such models are prohibitive under the current periodic boundary condition but possible under the proposed helical boundary conditions. Thus, a symmetry-adapted atomistic modeling tool will be created by augmenting an existing first-principles density functional theory solver with helical boundary conditions. In conjunction with a symmetry adapted Cauchy Born rule, this tool will allow for importing the accurate atomic-level physics into the large-scale continuum models. Using nanotubes and nanobelts as test beds, nanomechanical models will be established for isotropic one atom thick carbon nanotubes, and anisotropic/piezoelectric few atoms thick SiGe/Si and ZnO nanobelts. During this research, first-principles calculations will be performed in order to obtain an unprecedented understanding of the response of graphene, SiGe/Si, and ZnO ultra thin layers to stretching, rolling, and torsion. Traditional finite and discrete element modeling will be carried out to validate and test the utility of the created models. If successful, this research will lead to a versatile multiscale methodology that can be applied for other important nano-objects as well as for biological systems. The models created for nanotubes and nanobelts are viable for immediate exploitation in the context of the ongoing design and process modeling efforts directed toward increasing performance and yield. The proposed research facilitates the incorporation of nanomechanics into the engineering curriculum, and outreach and mentoring activities: The growing interest in nanomechanics and the lack of a suitable textbook are strong indications that the Computational Nanomechanics book will be popular. The technology-based educational tool. Engage and Communicate, uses widely available technology (PC/Mac and Internet). This will make it easier to engage students and faculty, including high school students and members of underrepresented groups from various universities, in science and engineering activities.