A Particle-Based Implicit Solvent Model for Short-Range Oscillatory Solvation Forces

Experimental and theoretical studies have demonstrated that when two parallel surfaces approach within nanometer separations, ordered layering of solvent molecules in the confined region gives rise to pronounced short-range, periodic oscillatory forces. However, the high computational expense of explicit solvent simulations has hindered detailed exploration of how these oscillatory forces regulate colloidal assembly dynamics. We develop an implicit solvent model for surfaces grafted with nonpolar ligands in nonpolar solvents, which resolves angle-dependent oscillatory solvation forces with molecular-level fidelity and computational efficiency, parametrized using explicit-solvent potential of mean force profiles. Microsecond-scale implicit solvent simulations of colloidal systems containing hundreds of nanoparticles further uncover that assembly pathways and phase behavior critically depend on particle shape and size. This efficient modeling framework offers a robust theoretical and numerical tool for elucidating solvent-mediated self-assembly mechanisms and for precision control of colloidal architectures.