Structure-based coarse-graining for inhomogeneous liquid polymer systems.

Area of Science:

• Computational chemistry
• Materials science
• Statistical mechanics

Background:

• The iterative Boltzmann inversion (IBI) method derives coarse-grained (CG) potentials from atomistic data.
• IBI-derived potentials are sensitive to thermodynamic conditions, limiting their use in inhomogeneous systems.
• Existing methods struggle to accurately model systems with varying densities and interfaces.

Purpose of the Study:

• To develop a robust coarse-graining scheme for generating nonbonded potentials applicable to both bulk and inhomogeneous systems.
• To create CG potentials that are transferable across different density regimes and interfaces.
• To provide a practical method for accurate CG modeling of complex materials.

Main Methods:

• A structure-based coarse-graining scheme was developed, refining CG nonbonded potentials using radial distribution functions (RDFs) from atomistic simulations.
• The method incorporates an optimized initial guess and minimal refinement to prevent over-transfer of many-body effects.
• Coarse-graining was applied to a liquid perfluoropolyether (PFPE) film on a carbon surface to test its applicability to inhomogeneous systems.

Main Results:

• The developed CG scheme successfully generated nonbonded potentials applicable to various density conditions.
• The CG model accurately reproduced structural and density distribution functions for bulk PFPE.
• The model also favorably reproduced properties at liquid-vacuum and liquid-solid interfaces.

Conclusions:

• The proposed structure-based coarse-graining scheme provides accurate nonbonded potentials for inhomogeneous systems.
• This approach overcomes limitations of traditional methods like IBI for systems with varying densities.
• The method offers a practical and effective way to model complex interfaces in materials science.