A Novel Approach for the Development of Accurate ab inito Potential Energy Surfaces for Atomistic Simulations of MEMS Applications

这项研究的目的是提出一种综合的方法，利用从头算量子力学势能面和扩展基组在高水平计算的力场，在原子水平上进行模拟。该方法包括(1)材料截止半径内的非平衡团簇的电子结构计算(使用Gauss2003软件)，(2)使用MD方法和新颖的采样程序对在动力学中重要的系统配置空间的子集进行采样，以及(3)使用神经网络(NN)在计算点之间进行精确内插，并使用早期停止和正则化方法来改进网络性能。该方法的准确性将在包括纳米切割、摩擦学和材料测试在内的广泛制造工艺中进行测试和验证。分子动力学(MD)和蒙特卡罗(MC)模拟可用于对包括超精密加工、磨削和抛光以及材料测试和摩擦学在内的广泛制造过程进行建模。该方法不仅适用于基础化学、物理、生物等科学领域，而且适用于工程领域，是一种普遍适用的方法。这个问题将由来自化学、电气工程、机械工程、数学和材料科学背景的研究人员组成的跨学科小组与这些学科的研究生和本科生(通过NSF REU计划)合作解决。所进行的研究将完全与研究生教育相结合。我们打算与这一领域的行业和国家实验室进行互动。将努力招募在美国出生的妇女、少数民族和身体残疾的学生参与这个项目。

The objective of the proposed research is to present an integrated approach for conducting simulations at the atomistic level using ab initio quantum mechanical potential-energy surfaces and force fields computed at high-level with extended basis sets. The approach involves (1) electronic structure calculations (using GAUSSIAN 2003 software) of non-equilibrium clusters within the cut-off radius of a material, (2) sampling of the subset of the system configuration space that is important in the dynamics using MD methods augmented with novelty sampling procedures, and (3) accurate interpolation between the computed points using neural network (NN) with early stopping and regularization methods employed to improve network performance. The accuracy of the method will be tested and validated in wide range of manufacturing processing including nanometric cutting, tribology, and material testing. This approach will be extended this to other applications involving carbon nanotubes and synthesis of microcrystalline diamond by chemical vapor deposition (CVD).Molecular dynamics (MD) and Monte Carlo (MC) simulations can be applied for modeling a wide range of manufacturing processes including ultraprecision machining, grinding, and polishing as well as materials testing, and tribology. The method proposed is a generalized method in that it can be applied for a wide range of fields in engineering as well as in basic chemistry, physics, biology, and other scientific fields of endeavor. This problem will be addressed by an interdisciplinary group of researchers from chemistry, electrical engineering, and mechanical engineering, math and materials science background working with graduate and undergraduate (through NSF REU program) students from these disciplines. Research conducted will be fully integrated with the graduate level education. We intend to interact with industry and national laboratories involved in this area. Attempts will be made to recruit U.S. born women, minority, and physically impaired students to work on this project.