Theoretical study of transition metal complex in crystal: Improvement of QM/MM approach for molecular crystal

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K14437
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Physical chemistry
• Research Institution: Kyoto University
• Principal Investigator: Aono Shinji 京都大学, 福井謙一記念研究センター, 特定研究員 (70750769)
• Research Collaborator: Sakaki Shigeyoshi
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: QM/MM法 / 分子結晶 / 結晶効果 / 吸収・発光スペクトル / 異性化反応 / 混合原子価性

Outline of Final Research Achievements

The theoretical study of luminescent spectra, chemical reactions, and mixed-valence characters in molecular crystals is a challenging research target. For such investigations, we have improved the crystal model and modified the quantum mechanics/molecular mechanics (QM/MM) method based on the periodic MM crystal model with the self-consistent point charges. In our method, QM molecule is embedded in infinitely periodic MM crystal, the point charges and geometries of which are determined as mirror image of the QM molecule in the self-consistent field manner by applying the translational and symmetrizing operations to the subunit of the minimum unit cell. We compared the molecular properties and reactions in crystal with those in gas phase and solution, discussed the characteristic differences, and successfully elucidated the reason why from the microscopic molecular viewpoints.

Free Research Field

理論化学

Academic Significance and Societal Importance of the Research Achievements

本研究は、これまで理論的研究がほとんど行われてこなかった分子性結晶内での遷移金属錯体の電子状態と構造、分子物性、反応性を明らかにした研究である。我々の行ったQM/MM法はQM分子-MM分子間相互作用の記述精度に問題が残るが、着目するQM分子をCCSD(T)法やCASPT2法などの高精度な電子状態計算で扱えるという点は、現在普及している平面波DFT法では扱えない学術的問題に対しても解答を与え得る。また本研究で行った遷移金属錯体から成る分子結晶は、機能材料への応用の面でも期待でき、その分子機能制御の足掛かりになる事は社会発展の上でも意義がある。