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.