Mika Matsuo | Searcharxiv

arXiv2026

Solvent Mixing Effect on Free-Energy Barrier and Stability for Molecular Recognition Driven by the Translational Motion of Solvent Molecules

We calculated the potentials of mean force (PMFs) between a ring-like host and a spherical guest in a solvent mixture. We adopted hard-body interactions between particles to discuss the effects of solvent-particle translational motion. The PMFs were obtained using the three-dimensional Ornstein-Zernike equation coupled with the modified hypernetted-chain closure (3D-MHNC-OZ theory). The entropic stabilization at the recognition site is confirmed, and a free-energy barrier wall is observed surrounding it. The free-energy barrier for the solvent mixture is much lower than that for the one-component solvent. Similar barrier reduction for the association of two spherical solute molecules has also been reported, and the mixing effect also reduced the dimerization stability. By contrast, the mixing effect does not significantly reduce recognition stability in the present study. In this respect, the behavior of the host-guest association is different from that of the association of two spherical solute molecules.

cond-mat.soft↗

arXiv2023

Spatial distribution of reduced density of hard spheres near a hard-sphere dimer: Results from three-dimensional Ornstein-Zernike equations coupled with several different closures and from grand canonical Monte Carlo simulation

We calculated the spatial distribution of reduced density and pair distribution function (PDF) of solvent hard spheres near a solute using three-dimensional Ornstein-Zernike (OZ) equations coupled with closures in which Percus-Yevick (PY) and hypernetted-chain (HNC) approximations were employed or bridge functions (BFs) proposed by Verlet, Duh and Henderson, and Kinoshita were incorporated. The solute was formed by two solvent hard spheres in contact with each other, with the result that the system is not radial-symmetric, necessitating the extension of Verlet, Duh-Henderson, and Kinoshita BFs to three-variable functions considered in the Cartesian coordinate system. The results were compared with those from grand canonical Monte Carlo (MC) simulation. In terms of the PDF, HNC is superior to PY in the sense that the results from the former are closer to those from MC. The incorporation of the three BFs makes the results further closer to those from MC. The three BFs share almost the same performance for a solute immersed in a one-component solvent at the infinite-dilution limit. Analyses on the triplet distribution function (TDF) were also performed. It was found that in terms of the TDF the incorporation of the BFs does not necessarily lead to improvement.

cond-mat.soft↗