Theory of chemical binding in beyond-Born-Oppenheimer chemistry and its applications to complex molecular systems

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H00373
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Takatsuka Kazuo 京都大学, 福井謙一記念研究センター, 研究員 (70154797)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 実時間電子ダイナミクス / 電子・スピン流化学 / 非断熱遷移動力学 / 励起状態動力学 / 超高速化学反応 / 化学結合論 / 化学反応理論

Outline of Final Research Achievements

We have studied a new class of chemical dynamics to be found in molecular electronic excited states embedded in densely quasi-degenerate state manifolds, in which a huge fluctuation is induced due to persisting multidimensional nonadiabatic transitions among the states. The relevant phenomena can result in intramolecular energy redistribution, which we call intramolecular nonadiabatic electronic-energy redistribution. Despite the huge fluctuation, strong chemical bonding coexists to assist the molecules to survive. Such complex electronic excited states are found in, for example, boron and carbon clusters. Those excited states have been analyzed with our developed energy natural orbitals (ENO). It turns out that ENO energy spectra are composed of four robust layers of different physical natures. In the layer structure, the physical origin of the robust chemical bonds has been identified. We also have found novel electronic-state quantum chaos behind the fluctuation.

Free Research Field

理論化学動力学

Academic Significance and Societal Importance of the Research Achievements

本研究は、分子の電子状態理論（いわゆる量子化学）の新しい領域を開拓し、将来発展するであろう非断熱電子動力学理論の礎を構築するものである。特に、原子核と電子の多次元多状態非断相互作用、アト秒レベルの実時間電子流・電子エネルギー流・スピン流の実時間追跡、などを解析可能とし、従来の理論的枠組みの中でも有用な手法として応用可能な高励起状態化学の解析手法、などを提案している。