Collective Dynamics and Resonances of Phonons and Dislocations in Thermal Transport

非技术总结该奖项支持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的研究。位错是一种普遍存在的缺陷，它涉及晶体材料原子排列的突然不规则性(如出现额外的一排原子)。当材料处于热载荷或机械载荷下时，它们通常可以在材料中移动。晶体中的原子发生振动，振动的幅度随着温度的升高而增加。位错在晶体中的运动可以通过它们与这些振动的相互作用来影响，其方式类似于波浪对船在水中移动时的运动的影响。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输的影响。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重要意义，例如可以将热能转换为电能的热电材料，以实现绿色经济。该奖项还支持该团队的教育和外展活动。在这个项目期间，PIS将设计计算系列讲座和微型项目，以在每年夏天培训本科生。专业人士亦会接触妇女和少数族裔学生，以及肢体残疾学生，探讨他们的研究兴趣，并为他们提供研究经验。在该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研讨会，讨论位错与晶体振动之间的相互作用对热传输的作用。技术总结该奖项支持一些研究，这些研究将阐明位错和声子之间的相互作用的微观过程及其对宏观材料现象的影响，包括塑性流动、内耗和热阻。声子-位错相互作用的一般描述能够提供与主要实验结果的定量一致一直是一个重大的挑战，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一种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行原子-连续谱模拟的多尺度方法来应对这一挑战。这将能够准确地描述声子热输运研究中的位错，以及用物理过程的多尺度细节来可视化声子散射的瞬时过程，以确定潜在的机制。该奖项还支持该团队的教育和外展活动。在这个项目期间，PIS将设计计算系列讲座和微型项目，以在每年夏天培训本科生。专业人士亦会接触妇女和少数族裔学生，以及肢体残疾学生，探讨他们的研究兴趣，并为他们提供研究经验。在该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研讨会，讨论位错与晶体振动相互作用在热传输中的作用。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.