Hybrid molecular-continuum simulations using smoothed dissipative particle dynamics.

Area of Science:

• Computational physics and chemistry
• Multiscale modeling and simulation
• Fluid dynamics

Background:

• Bridging atomistic detail with continuum descriptions is crucial for complex systems.
• Existing methods face challenges in seamlessly integrating different resolution scales.
• Smoothed dissipative particle dynamics (SDPD) offers a promising route for coarse-grained simulations.

Purpose of the Study:

• To develop and validate a novel multiscale simulation methodology.
• To couple atomistic molecular dynamics (MD) with smoothed dissipative particle dynamics (SDPD) across varying resolutions.
• To address chemical potential gradients at the interface between different simulation domains.

Main Methods:

• Coupling atomistic molecular dynamics (MD) with smoothed dissipative particle dynamics (SDPD) simulations.
• Implementing a pairwise thermodynamic force in a buffer region to manage resolution differences.
• Utilizing a multi-resolution SDPD approach for continuum domain modeling.

Main Results:

• The methodology correctly reproduces thermodynamic properties of a Lennard-Jones fluid across scales.
• Accurate simulation of non-equilibrium phenomena, including the startup of shear flow.
• Demonstrated robustness with shear forces parallel and perpendicular to the interface, yielding correct transient velocity profiles.
• Successful triple-scale simulation coupling MD and two SDPD regions of different resolutions.

Conclusions:

• The developed multiscale simulation technique effectively couples atomistic and continuum domains.
• The method is suitable for both equilibrium and non-equilibrium problems in fluid dynamics.
• This approach enables systematic integration of atomistic models with arbitrarily coarse continuum fluid domains.