# Couple microscale periodic patches to simulate macroscale emergent dynamics

## TL;DR

This paper introduces a method to connect microscale periodic patches to predict macroscale dynamics efficiently, using control techniques to simulate heat transport in atomistic systems.

## Contribution

It develops a novel scheme that leverages periodic microscale simulators with control strategies to accurately predict macroscale behavior.

## Key findings

- Effective prediction of heat transport using proportional control
- Theoretical analysis confirms efficiency and effectiveness
- Guidelines for optimal control parameters

## Abstract

This article proposes a new way to construct computationally efficient `wrappers' around fine scale, microscopic, detailed descriptions of dynamical systems, such as molecular dynamics, to make predictions at the macroscale `continuum' level. It is often significantly easier to code a microscale simulator with periodicity: so the challenge addressed here is to develop a scheme that uses only a given periodic microscale simulator; specifically, one for atomistic dynamics. Numerical simulations show that applying a suitable proportional controller within `action regions' of a patch of atomistic simulation effectively predicts the macroscale transport of heat. Theoretical analysis establishes that such an approach will generally be effective and efficient, and also determines good values for the strength of the proportional controller. This work has the potential to empower systematic analysis and understanding at a macroscopic system level when only a given microscale simulator is available.