Quantum Mechanical Simulations of Nanoindentation of Al Thin Film

TL;DR

This paper introduces QCDFT, a multiscale simulation method combining quasicontinuum and density functional theory, applied to nanoindentation of Al thin films, revealing how Mg impurities enhance strength.

Contribution

The paper develops QCDFT, a novel multiscale modeling approach integrating DFT with QC for large-scale simulations, applied here to nanoindentation of Al films.

Findings

Mg impurities increase the strength of Al thin films.

QCDFT effectively simulates multi-million atom systems.

Impurities alter the mechanical response during nanoindentation.

Abstract

QCDFT is a multiscale modeling approach that can simulate multi-million atoms effectively via density functional theory (DFT). The method is based on the framework of quasicontinuum (QC) approach with DFT as its sole energetics formulation. The local QC energy is calculated by DFT with Cauchy-Born hypothesis and the nonlocal QC energy is determined by a self-consistent embedding approach, which couples nonlocal QC atoms to the vertices of the finite-elements at the local QC region. The QCDFT method is applied to a nanoindentation study of an Al thin film in the presence and absence of Mg impurities. The results show that the randomly distributed Mg impurities can significantly increase the ideal and yield strength of the Al thin film.