Addressing Surface Effects at the Particle-Continuum Interface in a Molecular Dynamics and Finite Elements Coupled...

Area of Science:

• Multiscale modeling
• Computational materials science
• Polymer physics

Background:

• Atomistic-to-continuum coupling methods integrate computational efficiency with accuracy for molecular simulations.
• The Capriccio method connects finite elements (FE) with molecular dynamics (MD) but struggles with interfacial artifacts in amorphous polymers.
• Interfacial coupling artifacts significantly hinder accurate simulations of polymer microstructure and behavior.

Purpose of the Study:

• To develop a robust atomistic-to-continuum coupling method that overcomes interfacial artifacts in polymer simulations.
• To accurately reproduce structural and mechanical properties of polymers using multiscale modeling.
• To enable detailed molecular-level analysis of complex deformations in polymers.

Main Methods:

• Extension of the Capriccio method by incorporating a layer of passive atoms at the particle-continuum interface.
• The passive atoms mimic continuum behavior, providing necessary interactions to the inner particle region.
• Validation through reproduction of properties like density, stress, Young's modulus, and Poisson's ratio.

Main Results:

• Successfully reproduced structural and mechanical properties comparable to periodic boundary conditions.
• Demonstrated accurate simulation of nonaffine deformation using a bending test.
• Eliminated significant interfacial coupling artifacts in amorphous polymer simulations.

Conclusions:

• The revised method effectively suppresses interface effects, enabling accurate multiscale simulations of polymers.
• Provides a framework for applying complex deformations in molecular dynamics and analyzing phenomena like fracture.
• Enhances the capability of engineering communities to study molecular-level material behavior.