Theoretical analyses of phonon-related properties of layered materials and their local structures

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02544
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 28020:Nanostructural physics-related
• Research Institution: The University of Tokyo
• Principal Investigator: Watanabe Satoshi 東京大学, 大学院工学系研究科(工学部), 教授 (00292772)
• Co-Investigator(Kenkyū-buntansha): 南谷 英美 分子科学研究所, 理論・計算分子科学研究領域, 教授(兼任) (00457003) ; 清水 康司 東京大学, 大学院工学系研究科(工学部), 助教 (00838378)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 密度汎関数法 / フォノン / 層状物質 / 電子フォノン相互作用 / 熱伝導 / 機械学習ポテンシャル / 点欠陥

Outline of Final Research Achievements

We conducted quantitative evaluation of phonon-related properties of layered materials and clarification of the effects of defects, etc., as well as development of computational methods for this purpose. For the computational methods, we succeeded in improving the numerical accuracy of electron-phonon interaction matrix elements with a small number of reciprocal space sampling points, establishing a high-accuracy prediction method for phonon bands and thermal conductivity using machine-learning potential (MLP), developing MLP that takes account of defect charge states, developing a new structural descriptor for MLP with persistent diagram, etc. For the property analyses, we found increases in the superconducting transition temperature under both tensile and compressive strains in Li-doped bilayer MoS2, a remarkable change in the phonon bands of GaN with nitrogen vacancies by their charge states, a strong correlation between the thermal conductivity and density of amorphous carbon, etc.

Free Research Field

計算材料物理

Academic Significance and Societal Importance of the Research Achievements

全世界的に求められている情報処理やエネルギー変換の一層の高度化・高性能化を実現できる材料として層状物質は期待されている。その性能を発揮させる上でフォノン関連物性とそれに及ぼす欠陥等の影響の理解は重要である。本研究では、層状物質のフォノン関連物性を欠陥等の影響まで含めて予測・解析することに大きく貢献しうる計算法を開発でき、熱伝導率と構造の相関や超伝導転移温度と歪みの関係等について様々な新たな知見を得ることができた。この点で学術的・社会的意義が大きい。