A study on the OZ theory to improve the accuracy of thermodynamic quantities

2023 Fiscal Year Final Research Report

• Project/Area Number: 16K05659
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: Ehime University
• Principal Investigator: MIYATA Tatsuhiko 愛媛大学, 理工学研究科(理学系), 講師 (70390648)
• Project Period (FY): 2016-04-01 – 2024-03-31
• Keywords: 溶媒和自由エネルギー / OZ理論 / RISM理論 / 分子動力学シミュレーション / closure近似 / hybrid closure / Lennard-Jones流体 / クーロン系

Outline of Final Research Achievements

The solvation free energy plays the central role in discussing the thermodynamic stability of solutes in solution. While the integral equation method including the OZ theory has an advantage of low computational cost, the solvation free energy obtained by the method suffers from a significant error coming from the approximation assumed in the theories. This study began with improving the accuracies for monatomic molecular systems, and aimed to improve the 3D-RISM theory through a bottom-up approach. This study has proposed the SEB correction, which is defined as a bridge function to have an effect of enlarging the sigma parameter of the LJ potential. This correction can be widely used not only for monatomic molecular systems but also for polyatomic ones. Furthermore, the SEB is found to improve the accuracy of the hydration free energy obtained from the 3D-RISM theory.

Free Research Field

物理化学

Academic Significance and Societal Importance of the Research Achievements

タンパク質の安定構造やリガンド結合などの予測計算では通常、分子動力学法が使われる。分子動力学法は結果が正確であることが期待される反面、計算コストが大変重く、タンパク質などの複雑な分子の自由エネルギー計算ではスーパーコンピュータが不可欠である。一方、積分方程式理論は計算コストが軽い反面、理論に含まれる近似の影響により計算結果が不正確となる場合がある。本研究成果は溶媒和自由エネルギーに関して、計算コストの軽さと計算結果の正確性を両立し得るものであり、今後は複雑な分子系への応用が期待される。