First-principles study of various charge ordered states of molecular conductors

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17756
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: Kumamoto University (2017-2018); National Institute for Materials Science (2016)
• Principal Investigator: Tsumuraya Takao 熊本大学, 大学院先導機構, 助教 (00619869)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 電子構造 / 分子性導体 / 強相関電子系 / 電荷秩序 / 磁性

Outline of Final Research Achievements

Molecular conductors show a rich variety of ground states such as antiferromagnetic state, quantum spin liquid, superconductivity, charge ordering (CO), spin-density wave ordering, spin-Peierls state, and so on. Such a richness of properties originates from relatively large Coulomb interactions. Among them, CO state is an electronic state where charge density becomes disproportionate between molecular sites. However, to the authors’ knowledge, there is no report of first principles density-functional theory (DFT) study on insulating states mentioned above. Standard exchange-correlation functionals often fail to reproduce the insulating states of the strongly correlated systems. Thus, we need accurate, reliable, but efficient computational approaches which can be applied with a reasonable cost. In this work, we studied the electronic and structural properties of experimentally showing CO insulating ground state using hybrid functional calculations.

Free Research Field

物性物理学

Academic Significance and Societal Importance of the Research Achievements

分子性固体の電荷不均一状態、そしてそれを実現する電子格子相互作用を定量的に明らかにする第一原理計算手法を確立することは学術的に極めて重要な課題であり、本研究が成功すれば分子性固体が示す多様な物性を理解するための情報を増やすことができた。また、本研究課題では日本で開発された分子性物質や現象を対象としており、電荷の不均一性の起源についての本質的理解を与えることができ、実験研究者に直接フィードバックをもたらすことができた。