Fundamental Nanomechanics with SCC-DFTB Objective Molecular Dynamics

本奖项的研究目的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。因为这些结构的存在尺度与原子间距离相当，所以原子的细节对于理解它们的行为至关重要。计划的纳米力学计算与当前的量子方法是禁止的，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一致-电荷密度-功能紧密结合的结合，它们成为可能。这种耦合依赖于埃瓦尔德方法对螺旋电荷分布的推广。初步结果表明，这种推广是可行的，可以实现高效的纳米结构和生物分子模拟。如果成功，该方法将首次允许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。淀粉样蛋白原研究旨在了解关键的原子细节、力学特性以及多态性与力学反应之间的相关性，将有助于阐明阿尔茨海默病和其他朊病毒疾病的分子机制。此外，它们将对淀粉样蛋白原纤维的中尺度建模和纳米材料的仿生发展产生影响。螺旋氧化锌纳米带的模拟，着重于超弹性、屈曲、断裂和机械能到电能的转移，将产生一个现象学朗道模型，用于设计功率纳米发电机。计划的研究与教育计划相结合，促进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群体参与。一个网络模块将为明尼苏达州公众说明与朊病毒疾病相关的潜在影响，以及负责纳米能量储存的机制。这个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.