Collective Dynamics and Resonances of Phonons and Dislocations in Thermal Transport

该奖项支持的研究将使用原子分辨率计算机模型来确定晶体材料中位错和原子振动之间相互作用的性质。位错是一种普遍存在的缺陷，涉及晶体材料原子排列的突然不规则性（如多出一排原子）。当材料受到热载荷或机械载荷时，它们通常可以在材料中移动。晶体中的原子振动，振动的振幅随着温度的升高而增大。通过晶体的位错运动可以受到它们与这些振动的相互作用的影响，其影响方式类似于波对船在水中运动的影响。这项研究将量化这种相互作用，并确定它们对通过材料的热传递的影响。这项研究的结果将对许多热传输应用的新材料的设计具有根本性的重要性，例如可以将热量转化为电能的绿色经济的热电材料。该奖项还支持该团队的教育和推广活动。在该项目期间，每年夏天，pi将设计计算系列讲座和小项目来训练本科生。项目还将面向女性和少数民族学生以及身体残疾的学生，探索他们的研究兴趣，并为他们提供研究经验。在这个项目下开发的数据集和源代码将免费提供给计算材料科学界。研究小组还将在国际或国内会议上组织一次专题讨论会，讨论位错与晶体振动的相互作用对热传递的影响。该奖项支持的研究将阐明描述位错和声子之间相互作用的微观过程，以及它们对宏观材料现象的影响，包括塑性流动、内摩擦和热阻。声子位错相互作用的一般描述可以提供与主要实验结果的定量一致，这是一个重大挑战，这限制了我们对这种相互作用及其对热输运的影响的理解。本研究旨在通过建立从高保真原子间势的机器学习到耦合位错动力学和声子输运的并发原子连续体模拟的多尺度方法来解决这一挑战。这将能够准确描述声子热输运研究中的位错，以及声子散射的瞬态过程的可视化，以及物理过程的多尺度细节，以确定潜在的机制。该奖项还支持该团队的教育和推广活动。在该项目期间，每年夏天，pi将设计计算系列讲座和小项目来训练本科生。项目还将面向女性和少数民族学生以及身体残疾的学生，探索他们的研究兴趣，并为他们提供研究经验。在这个项目下开发的数据集和源代码将免费提供给计算材料科学界。研究小组还将在国际或国内会议上组织一次专题讨论会，讨论位错与晶体振动的相互作用对热传递的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis award supports research that will use atomic resolution computer models to determine the nature of interactions between dislocations and atomic vibrations in crystalline materials. Dislocations are ubiquitous defects that involve a sudden irregularity (such as the appearance of an extra row of atoms) in the atomic arrangement of crystalline materials. They often can move through the material when the material is under thermal or mechanical loading. The atoms in a crystal vibrate, with the amplitude of the vibrations increasing with temperature. The movement of dislocations through the crystal can be affected by their interactions with these vibrations in a manner similar to the effect that waves have on the motion of a boat as it moves through the water. This research will quantify such interactions and determine their effect on heat transport through the material. The results of this research will be of fundamental importance to the design of new materials for many applications of heat transport, such as thermoelectrics that can convert heat to electrical energy for a green economy. This award also supports the team’s educational and outreach activities. The PIs will design computational lecture series and mini projects to train undergraduate students every summer during the period of this project. The PIs will also reach out to women and minority students, and students with physical disabilities, to explore their research interests and provide them with research experiences. The datasets and source codes developed under this project will be made freely available to the computational materials science community. The research team will also organize a symposium at an international or national conference on the role of interactions of dislocations with crystal vibrations on heat transport.TEHCNICAL SUMMARYThis award supports research that will elucidate the microscopic processes that describe the interaction between dislocations and phonons and their implications for macroscopic materials phenomena, including plastic flow, internal friction, and thermal resistance. A general description for phonon-dislocation interaction that can provide a quantitative agreement with major experimental results has been a significant challenge, which has limited our understanding of this interaction as well as its effect on thermal transport. This research aims to address this challenge by establishing a multiscale methodology from machine learning of high-fidelity interatomic potentials to concurrent atomistic-continuum simulation of coupled dislocations dynamics and phonon transport. This will enable an accurate description of dislocations in the studies of phonon thermal transport, as well as a visualization of the transient processes of phonon scattering with multiscale details of the physical processes to identify the underlying mechanisms. This award also supports the team’s educational and outreach activities. The PIs will design computational lecture series and mini projects to train undergraduate students every summer during the period of this project. The PIs will also reach out to women and minority students, and students with physical disabilities, to explore their research interests and provide them with research experiences. The datasets and source codes developed under this project will be made freely available to the computational materials science community. The research team will also organize a symposium at an international or national conference on the role of interactions of dislocations with crystal vibrations on heat transport.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.