Simulating Non-Equilibrium Processes over Extended Time- and Length-Scales using Parallel Accelerated Dynamics

技术摘要：该奖项支持计算研究和教育，以开发和应用并行温度加速动力学方法，以便能够对大系统规模和长时间的非平衡过程进行有意义的模拟。这项研究将建立在ITR奖下开发的并行动力学蒙特卡罗算法的基础上，并将为材料研究界的网络基础设施做出贡献。空间平行温度加速动力学的首次应用将集中在三个不同的问题上：(1)低温金属外延生长中的空位形成和退火，(2)低温半导体生长中的晶态到非晶态的转变，(3)辐照后的缺陷动力学。在低温下观察到了各种无法解释的现象，包括空位形成和应变诱导的土丘规则化，这使得第一个区域特别有趣。通过温度加速动力学来创建有效的计算算法来模拟扩展的长度和时间尺度上的非平衡过程的目标可能会对各种与材料相关的过程和材料的真实模拟产生重大影响。该奖项还支持相关的教育和外展活动。这个项目开发的方法和结果还将部分地整合到计算物理的本科和研究生联合课程中，以及薄膜和表面物理的研究生课程中，在该课程中，学生将学习新的理论进步和最先进的实施和经验评估技术。非技术总结：该奖项支持计算研究和教育，以开发和应用算法和软件来模拟时间尺度上的过程，这些算法和软件对基础科学很重要，但超出了传统模拟方法的范围。例如，由于运动方程积分所需的时间步长很小，分子动力学通常被限制在纳秒内。然而，重要的不常见事件通常发生在微秒甚至更长的时间尺度上。例如，晶体或薄膜生长过程中表面形态的演变，点缺陷在固体中的扩散，以及塑性应变过程中晶界的迁移。PI的目标是在之前ITR奖下进行的研究的基础上开发新的模拟工具。在实验的推动下，PI将把新的方法应用于材料生长和辐照后的材料动力学。新开发的算法和软件将有助于材料研究界的网络基础设施。该奖项还支持相关的教育和推广活动。该项目开发的方法和成果还将部分融入计算物理本科生和研究生联合课程，以及薄膜和表面物理研究生课程，在该课程中，学生将学习新的理论进步和最先进的实施和经验评估技术。

TECHNICAL SUMMARY:This award supports computational research and education to develop and apply methods of parallel temperature-accelerated dynamics to enable meaningful simulations of non-equilibrium processes for large system sizes and for long times. The research will build on algorithms for parallel kinetic Monte Carlo developed under an ITR award and will contribute to the cyberinfrastructure of the materials research community. The first applications of spatially parallel temperature-accelerated dynamics will focus on three distinct problems: (1) vacancy formation and annealing in low-temperature metal epitaxial growth, (2) crystalline to amorphous transition in low-temperature semiconductor growth, (3) dynamics of defects after irradiation. The observation of a variety of unexplained phenomena including vacancy formation and strain-induced mound regularization at low temperatures makes the first area particularly interesting. The goal of creating efficient computational algorithms for the simulation of non-equilibrium processes over extended length- and time-scales via temperature accelerated dynamics is likely to have a significant impact on the realistic simulations of a broad variety of materials-related processes and materials. This award also supports related educational and outreach activities. The methods and results developed from this project will also be integrated in part into a joint undergraduate-graduate course on Computational Physics and into a graduate course on Thin-Films and Surface Physics in which students will learn about new theoretical advances and state-of-the-art implementation and empirical evaluation techniques.NON-TECHNICAL SUMMARY:This award supports computational research and education to develop and apply algorithms and software to simulate processes on time scales that are important to the underlying science but out of the range of conventional simulation methods. For example, molecular dynamics is generally limited to nanoseconds because of the small time-step required for the integration of the equations of motion. However, important infrequent events often take place on a time scale of microseconds or even longer. Examples include the evolution of the surface morphology during crystal or film growth, the diffusion of point defects in solids, and the migration of grain boundaries during plastic strain. The PI aims to build on research performed under a previous ITR award to develop new simulation tools. Motivated by experiment, the PI will apply the new methods to materials growth and the dynamics of materials after irradiation. The newly developed algorithms and software will contribute to the cyberinfrastructure of the materials research community.This award also supports related educational and outreach activities. The methods and results developed from this project will also be integrated in part into a joint undergraduate-graduate course on Computational Physics and into a graduate course on Thin-Films and Surface Physics in which students will learn about new theoretical advances and state-of-the-art implementation and empirical evaluation techniques.