Hyperdynamics simulations with ab initio forces.

Area of Science:

• Computational Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Ab initio molecular dynamics (MD) simulations are computationally expensive for studying slow processes like defect diffusion.
• Accelerating these simulations is crucial for understanding materials behavior at longer timescales.

Purpose of the Study:

• To develop and implement an efficient hyperdynamics method within an ab initio framework.
• To investigate the diffusion mechanisms of lithium atoms and silicon vacancies in silicon.

Main Methods:

• Incorporation of the hyperdynamics method into ab initio calculations using a locally optimal rotation method.
• Calculation of potential derivatives and force calls per molecular dynamics (MD) step.
• Direct MD simulations and hyperdynamics simulations for comparative analysis.

Main Results:

• Successfully simulated defect diffusion in silicon with boost factors up to 10^5.
• Identified complex diffusion processes for lithium atoms and silicon vacancies.
• Obtained diffusion coefficients consistent with direct MD results.

Conclusions:

• The developed hyperdynamics approach is efficient and applicable for ab initio MD simulations.
• This method significantly accelerates the study of defect diffusion in materials like silicon.
• The findings provide valuable insights into the diffusion mechanisms of point defects.