Boundary Conditions for Molecular Dynamics Simulations of Solids

固体分子动力学模拟的边界条件

• 批准号: 0609610
• 负责人: Xiantao Li
• 金额: $ 12.64万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-15 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0609610&HistoricalAwards=false
• 关键词: Boundary; Conditions; Molecular; Dynamics; Simulations

Molecular dynamics models materials at the level of atomic scale. In a computer simulation one follows the motion of the atoms, which obeys Newton's second law. For crystalline solids, molecular dynamics offers a microscopic description of the crystal and defect structure, which is ultimately responsible for the overall material properties. It offers more insight on why the material behaves the way it does, and it has become an extremely important tool in material modeling and simulations. However due to the computational complexity, such a simulation can only be conducted for a small system. Typically it is focused around material defects where the deformation is quite large, and the atoms in the far field are eliminated. Such a truncation procedure creates artificial boundaries, where boundary conditions have to be imposed in order to take into account the missing atoms. The boundary condition provides, for example, the position of the atoms at the boundary, which will be needed in the force calculation for the atoms inside the system, and therefore required to allow the simulation to proceed. Straightforward approaches often lead to wave reflection at the boundary and therefore severely deteriorate the simulation results. This project aims to develop systematic boundary conditions that serve the following purposes: (a) prevent wave reflection at the boundary; (b) maintain the external loading; (c) control the system temperature. These boundary conditions will greatly improve the accuracy and reliability of molecular dynamics simulations and will help to study the dynamics of material defects under various kinds of loading, and in different temperature regimes. The project also involves numerical analysis aspects and applications of these methods. The proposed research will expose the students to physical modeling, large-scale simulations, mathematical analysis, and interdisciplinary research.

分子动力学在原子尺度上模拟材料。 在计算机模拟中，人们遵循原子的运动，这遵循牛顿第二定律。 对于晶体固体，分子动力学提供了晶体和缺陷结构的微观描述，这最终决定了整体材料的性质。 它提供了更多关于材料行为方式的见解，并且它已成为材料建模和模拟中非常重要的工具。 然而，由于计算的复杂性，这样的模拟只能进行一个小的系统。 通常，它集中在材料缺陷周围，其中变形相当大，并且远场中的原子被消除。 这样的截断过程创建了人工边界，其中必须施加边界条件以考虑缺失的原子。 例如，边界条件提供了边界处原子的位置，这将在系统内部原子的力计算中需要，因此需要允许模拟进行。 直接的方法往往会导致波反射的边界，因此严重恶化的模拟结果。 该项目旨在制定系统的边界条件，以达到以下目的：（a）防止边界处的波反射;（B）保持外部载荷;（c）控制系统温度。 这些边界条件将大大提高分子动力学模拟的准确性和可靠性，并将有助于研究各种载荷下的材料缺陷的动力学，在不同的温度制度。 该项目还涉及这些方法的数值分析方面和应用。 拟议的研究将使学生接触物理建模，大规模模拟，数学分析和跨学科研究。