Fundamental Nanomechanics with SCC-DFTB Objective Molecular Dynamics

该奖项的研究目标是了解和模拟淀粉样纤维的螺旋结构和力学，以及螺旋状氧化锌纳米结构中的稳定性和机械能量存储。由于这些结构的存在规模相当于原子间的距离，原子细节对于理解它们的行为是必不可少的。目前的量子方法依赖于晶体固体的平移对称性，计划中的纳米机械计算是无法实现的。然而，随着新的客观分子动力学方法与自洽电荷密度-泛函紧束缚的耦合，它们成为可能。这种耦合依赖于提出的将Ewald方法推广到螺旋电荷分布。初步结果表明，这种泛化是可行的，可以实现高效的纳米结构和生物分子模拟。如果成功，该方法将首次在定量水平上评估现代材料和生命科学中螺旋结构上离散电荷分布产生的静电场。淀粉样原纤维研究旨在了解关键的原子学细节、机械特性以及多态和机械反应之间的相关性，将有助于阐明阿尔茨海默氏症和其他普恩病毒疾病的分子机制。此外，它们还将对淀粉样蛋白纤维的中尺度建模和纳米材料的仿生开发产生影响。螺旋状氧化锌纳米带的模拟主要集中在超弹性、屈曲、断裂以及机械能向电能的转换等方面，它将产生一个现象学的朗道模型，用于设计功率纳米发电机。计划中的研究与促进将纳米力学纳入工程课程的教育计划相结合；它还伴随着鼓励代表不足的少数族裔参与的努力。一个网络模块将为明尼苏达州的公众展示与普恩病毒疾病相关的潜在影响，以及负责纳米能量存储的机制。该模块将提供给明尼苏达州科学博物馆。

The research objective of this award is to understand and model the helical structure and mechanics of amyloid fibrils, and the stability and mechanical energy storage in helical zinc oxide nanostructures. Because these structures exist on a scale comparable to interatomic distances, atomistic detail is essential to understanding their behavior. The planned nanomechanical computations are prohibitive with current quantum methods, which are dependent on the translational symmetry of crystalline solids. They become possible, however, with the new objective molecular dynamics method coupled with the self-consistent-charge density-functional tight-binding. This coupling relies on a proposed generalization of the Ewald method to a helical charge distribution. Preliminary results indicate that this generalization is feasible and could enable efficient nanostructure and biomolecule simulations. If successful, the methodology will allow for the first time the evaluation of electrostatic fields generated by discrete charge distributions over helical structures in modern materials and life sciences on a quantitative level. The amyloid fibril studies, aimed at understanding key atomistic details, mechanical properties and correlations between polymorphism and mechanical response, will help elucidate molecular mechanisms in Alzheimer's and other prion diseases. Also, they will have implications for the meso-scale modeling of amyloid fibrils and for the biomimetic development of nanomaterials. The helical zinc oxide nanobelts simulations, focused on super elasticity, buckling, fracture, and the transfer of mechanical into electric energy, will produce a phenomenological Landau model useful for designing power nano-generators. The planned research is integrated with an educational program that facilitates the incorporation of nanomechanics into the engineering curriculum; it is also accompanied by efforts to encourage participation of underrepresented minorities. A cyber-module will illustrate for the Minnesota public underlying effects related to prion diseases, and mechanisms responsible for nano-energy storage. This module will be made available to the Minnesota Science Museum.