A Concurrent Multiscale Micromorphic Molecular Dynamics. Part I. Theoretical Formulation

TL;DR

This paper introduces a multiscale micromorphic molecular dynamics framework that seamlessly integrates atomistic, mesoscale, and continuum models, enabling accurate nanoscale simulations with arbitrary boundary conditions.

Contribution

It develops a novel multiscale micromorphic molecular dynamics model extending traditional molecular dynamics to multiple scales with rigorous theoretical justification.

Findings

Unified multiscale structure connecting atomistic and continuum models

Rigorous derivation of Andersen-Parrinello-Rahman dynamics as a special case

Potential for solving complex nanoscale engineering problems

Abstract

Based on a novel concept of multiplicative multiscale decomposition, we have derived a multiscale micromorphic molecular dynamics (MMMD)to extent the (Andersen)-Parrinello-Rahman molecular dynamics to mesoscale and macroscale. The multiscale micromorphic molecular dynamics is a con-current three-scale particle dynamics that couples a fine scale molecular dynamics, a mesoscale particle dynamics of micromorphic medium, and a coarse scale nonlocal particle dynamics of nonlinear continuum. By choosing proper statistical closure conditions, we have shown that the original Andersen-Parrinello-Rahman molecular dynamics can be rigorously formulated and justified from first principle, and it is a special case of the proposed multiscale micromorphic molecular dynamics. The discovered mutiscale structure and the corresponding multiscale dynamics reveal a seamless transition channel from atomistic scale to continuum scale and the intrinsic coupling relation among them, and it can be used to solve finite size nanoscale science and engineering problems with arbitrary boundary conditions.