Thermal conductivity is an important property for almost all applications involving heat transfer, ranging from energy and microelectronics to food processing and textiles. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate the thermal conductivity of any crystalline line compound from first principles [1,2] using expressions based on the phonon gas model (PGM)[3,4]. However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. New theories and methods are therefore needed to understand phonon transport in amorphous materials. In this letter, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silica (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments at all temperatures and anharmonic effects are included in the thermal conductivity calculation for all types of modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature, which conceptually should prevent them from moving energy to another location. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400K to 800K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.
Machine Learning Inter-Atomic Potentials Generation Driven by Active Learning: A Case Study for Amorphous and Liquid Hafnium dioxide
Leadership Computing Facility, Argonne National Laboratory（阿贡国家实验室领导计算设施）；Institute for Computational Physics, Universität Stuttgart（斯图加特大学计算物理研究所）；Applied Materials Division, Argonne National Laboratory（阿贡国家实验室应用材料部）；University of Cambridge（剑桥大学）；X-ray Science Division, Argonne National Laboratory（阿贡国家实验室X射线科学部）；Computational Science Division, Argonne National Laboratory（阿贡国家实验室计算科学部）
Synthesis of thin silicon dioxide layers with high E' center densities and investigation of the E' center spin relaxation dynamics for single spin readout applications
Resonant Coupling and the Non-Phononic Flat Band in Amorphous Solids
School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院）；Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院吴徵镒量子中心）；School of Science and Engineering, The Chinese University of Hong Kong (Shenzhen)（香港中文大学（深圳）理学院）
