(359g) A Combined Fluctuating Hydrodynamics and Molecular Dynamics Method for Simulating Complex Molecular Systems at the Nanoscale

Hydrodynamic fluctuations and solvation interactions are essential driving forces for the transport phenomena at the nanoscale, including inter- and intra-cellular flows and flows in nanofabricated devices. Although fully atomistic simulations can be used to model the structures and dynamics of molecular fluids, the accessible time- and length-scales are impractical for the mesoscopic-to-nanoscopic regime. Since most of computational cost for all-atom simulations in a liquid phase comes from the represention of solvent molecules, we developed a new methodology to model molecular fluids based on the framework of fluctuating hydrodynamics (FHD). Despite the success of this approach, coupling a field theoretic model with a particle-based molecular mechanical model remains a significant challenge. In this work, we present a newly developed methodology for combining FHD and MD simulations. Our strategy is to let the fluctuating fields directly interact with particles according to the thermodynamics of solvation and the principle of fluctuation-dissipation theorem; no buffer region or ad-hoc degrees of freedom are introduced. The direct coupling approach differs our method from other attempts of coupling field and particle models reported in the literature. The results of applying our combined FHD/MD method to a model system show that the scaling laws of both solvation free energy and the Stokes dynamics are accurately represented. The results of applying this method to simulate the assembly process and dynamic motions of nanpoparticles will also be presented.