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蛋白原纤维的螺旋结构和力学，以及螺旋氧化锌纳米结构的稳定性和机械能储存。 由于这些结构存在于与原子间距离相当的尺度上，原子细节对于理解它们的行为至关重要。计划中的纳米力学计算是禁止与当前的量子方法，这是依赖于晶体固体的平移对称性。然而，随着新的客观分子动力学方法与自洽的电荷密度泛函紧束缚方法的结合，它们成为可能。这种耦合依赖于所提出的推广的埃瓦尔德方法的螺旋电荷分布。初步结果表明，这种推广是可行的，可以实现有效的纳米结构和生物分子模拟。 如果成功的话，该方法将首次允许在现代材料和生命科学中的螺旋结构上的离散电荷分布所产生的静电场的定量评估。淀粉样蛋白原纤维的研究，旨在了解关键的原子细节，机械性能和多态性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朊病毒疾病的分子机制。此外，他们将有影响的淀粉样纤维的中尺度建模和纳米材料的仿生发展。螺旋状氧化锌纳米带的模拟，重点是超弹性，屈曲，断裂，并将机械能转换为电能，将产生一个现象学的朗道模型用于设计功率纳米发电机。 计划中的研究与一项教育计划相结合，该计划有助于将纳米力学纳入工程课程;同时还努力鼓励代表性不足的少数民族参与。 一个网络模块将为明尼苏达州公众说明与朊病毒疾病有关的潜在影响，以及负责纳米能量储存的机制。该模块将提供给明尼苏达科学博物馆。

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.