Finite temperature molecular dynamics study of unstable stacking fault free energies in silicon

TL;DR

This study uses molecular dynamics with the EDIP model to calculate the free energies of unstable stacking faults in silicon across temperatures, providing insights into the brittle-ductile transition.

Contribution

It introduces a MD-based approach with environment-dependent potentials to evaluate USF free energies in silicon as a function of temperature.

Findings

MD results agree with first-principles estimates

Transition from shuffle to glide plane dominance with temperature

Implications for brittle-ductile transition models

Abstract

We calculate the free energies of unstable stacking fault (USF) configurations on the glide and shuffle slip planes in silicon as a function of temperature, using the recently developed Environment Dependent Interatomic Potential (EDIP). We employ the molecular dynamics (MD) adiabatic switching method with appropriate periodic boundary conditions and restrictions to atomic motion that guarantee stability and include volume relaxation of the USF configurations perpendicular to the slip plane. Our MD results using the EDIP model agree fairly well with earlier first-principles estimates for the transition from shuffle to glide plane dominance as a function of temperature. We use these results to make contact to brittle-ductile transition models.