第147回

Understanding the dynamical behavior of liquids is a main subject of solution chemistry. Liquid phase is a complicated many-body system and its dynamics can not be understand only with tracing the motion of each molecule. Diffusion equation can be regarded as a simple model for characterizing such many-body dynamics in the long time regime. However, the equation does not consider the intermolecular interactions and molecular geometries, meaning that the equation can not be used to understand the phenomena at the microscopic level. In order to overcome the problems, dynamics theories for molecular liquids have been developed over the past few decades. The theories are based on reference interaction site model (RISM), an integral equation theory for molecular liquids, and Zwanzig-Mori projection operator method. Recently, we developed a molecular diffusion theory which is applicable to complicated systems such as electrolyte solutions for lithium-ion batteries, and constructed a fundament to investigate diffusion-controlled reactions in polyatomic molecule systems. In the theories, molecular diffusion is described as the time-evolution of the spatial distribution function for each solvent atom (interaction site) around a solute molecule. The function is obtained by solving the formulated equations analytically or numerically, and hence the theories are free from statistical error which sometimes appear as severe problems in simulation-based methods. In this talk, I’ll present our approaches in molecular diffusion based on statistical mechanics, together with some applications. At the end of the talk, I’ll briefly introduce the current research project in Sugita group (BDR), ligand binding process in a crowded environment.