ITR/AP: Large-Scale Quantum Mechanical Molecular Dynamics Simulations: Challenges, New Directions, and Applications to Carbon-Based Nanostructures

ITR/AP：大规模量子力学分子动力学模拟：碳基纳米结构的挑战、新方向和应用

• 批准号: 0112824
• 负责人: Chakram Jayanthi
• 金额: $ 45.6万
• 依托单位: University of Louisville Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0112824&HistoricalAwards=false
• 关键词: ITR; AP; Large; Scale; Quantum

This award is the result of a proposal submitted to the Information Technology Research initiative. Advances in computational materials science depend on the development of efficient and reliable computational methods for large-scale quantum mechanical molecular dynamics (MD) simulations. Linear-scaling or order-N (O(N)) methods have been developed with the aim of overcoming the bottleneck associated with the N3-scaling in the computation of the total energy and atomic forces in quantum mechanics-based simulations. Despite this progress, O(N)- ab initio-MD is still limited to systems containing relatively small numbrs of atoms because of the overhead associated with the self-consistent calculations in ab initio MD. On the other hand, MD schemes based on two-center tight-binding (TB) Hamiltonians are orders of magnitude faster than O(N)-ab initio-MD methods. However, they have been found to be unsatisfactory in systems where charge transfer or bond breaking/rebonding plays a significant role. Therefore, there is a pressing need for developing transferable semi-empirical Hamiltonians that would be superior to traditional two-center TB Hamiltonians, but would include all essential ingredients of ab initio Hamiltonians without being computationally excessive. The O(N)-MD scheme using such a Hamiltonian can predict accurately the properties of complex systems of large sizes.In this research a general scheme will be developed to construct such reliable and transferable semi-empirical Hamiltonians for materials (metal or semiconductor) in the framework of linear combination of atomic orbitals (LCAO) that explicitly includes the self-consistently (SC) determined charge transfer and environment-dependent (ED) multi-center interactions. The SCED-LCAO Hamiltonian will be implemented within the O(N)-MD scheme developed previously. Using O(N)/SCED-LCAO-MD as our simulation tool, we will investigate the properties of carbon multi-wall nanotubes and carbon nanorods, and evaluate their potential as components of molecular-scale devices. Specifically, we will study the following three projects of current interest: (1) Energetics, structure, electronic, mechanical and vibrational properties of carbon multiwall nanotubes (MWNT), (2) A study of the properties of contacts between metal elctrodes and MWNT, and (3) Energetics, structure, electronic, mechanical and vibrational peoperties of carbon nanorods (CNR). Project (2) will be done in collaboration with the experimetal group of Professor Alphenar of Lousiville, whereas project (3) will be done in collaboration with the experimental group of Professor Chen of Academia Sinica (Taiwan).%%%***

该奖项是提交给信息技术研究计划的提案的结果。计算材料科学的进步取决于大规模量子力学分子动力学（MD）模拟的高效可靠的计算方法的发展。线性标度或阶N （O(N)）方法的发展，旨在克服量子力学模拟中总能量和原子力计算中与n3标度相关的瓶颈。尽管取得了这些进展，但由于从头算MD的自洽计算带来的开销，O(N)-从头算MD仍然局限于包含相对较少原子数的系统。另一方面，基于双中心紧密结合（TB）哈密顿量的MD方案比O(N)-从头算MD方法快几个数量级。然而，在电荷转移或键断裂/重键起重要作用的系统中，它们被发现是不令人满意的。因此，迫切需要发展可转移的半经验哈密顿量，它将优于传统的双中心TB哈密顿量，但将包括从头算哈密顿量的所有必要成分，而不会计算过量。使用这种哈密顿量的O(N)-MD格式可以准确地预测大尺寸复杂系统的性质。在本研究中，我们将开发一个总体方案，在原子轨道线性组合（LCAO）的框架下，为材料（金属或半导体）构建这种可靠和可转移的半经验哈密顿量，其中明确包括自一致（SC）决定的电荷转移和环境相关（ED）多中心相互作用。SCED-LCAO的哈密顿量将在先前制定的O(N)-MD计划中实施。利用O(N)/SCED-LCAO-MD作为我们的模拟工具，我们将研究碳多壁纳米管和碳纳米棒的性质，并评估它们作为分子尺度器件组件的潜力。具体来说，我们将研究以下三个当前感兴趣的项目：(1)碳多壁纳米管（MWNT）的能量学、结构、电子、机械和振动特性，(2)金属电极与碳多壁纳米管之间接触特性的研究，以及(3)碳纳米棒（CNR）的能量学、结构、电子、机械和振动特性。项目(2)将与Lousiville的Alphenar教授的实验组合作完成，而项目(3)将与台湾中央研究院陈教授的实验组合作完成。%%%***