Atomistic molecular dynamics simulations of shock compressed quartz

Area of Science:

• Materials Science
• Computational Physics
• Geophysics

Background:

• Shock wave compression is crucial for understanding material behavior under extreme conditions.
• Atomistic simulations offer insights into material responses, complementing experimental shock wave studies.
• The BKS potential is a widely used model for silica but requires validation for dynamic compression scenarios.

Purpose of the Study:

• To construct the Hugoniot of quartz using atomistic non-equilibrium molecular dynamics simulations.
• To evaluate and modify the BKS potential for shock wave compression of quartz.
• To investigate quartz phase transitions under pressure.

Main Methods:

• Atomistic non-equilibrium molecular dynamics simulations.
• Utilizing a flyer-plate impactor setup in a 3D periodic boundary condition system.
• Implementing a geometry-optimized polar slab with surface dipole relaxation.
• Modifying the BKS semi-empirical potential.

Main Results:

• The modified BKS potential accurately reproduces experimental Hugoniot data for quartz up to 25 GPa.
• Significant divergence from experimental data is observed beyond 25 GPa.
• The BKS potential incorrectly favors the β-quartz phase over the α-quartz phase at zero temperature.
• A β → α phase transition in quartz is predicted at 6 GPa.

Conclusions:

• The modified BKS potential is suitable for simulating quartz under Earth core pressures but not for high-pressure shock wave studies.
• The BKS potential requires further refinement for accurate high-pressure shock wave simulations of quartz.
• The study highlights the importance of accurate interatomic potentials for predicting material behavior under extreme conditions.