A Multiscale Formulation for Reducing Computation Time in Atomistic Simulations

Abstract

Molecular dynamics simulations require significant computational resources to generate modest time evolutions. Large active forces lead to large accelerations, requiring subfemtosecond integration time steps to capture the resultant high-frequency vibrations. It is often necessary to combine these fast dynamics with larger scale phenomena, creating a multiscale problem. A multiscale method has been previously shown to greatly reduce the time required to simulate systems in the continuum regime. A new multiscale formulation is proposed to extend the continuum formulation to the atomistic scale. A canonical ensemble model is defined using a modified Nóse–Hoover thermostat to maintain the constant temperature constraint. Results show a significant reduction in computation time mediated by larger allowable integration time steps.