Structure and bonding of dense liquid oxygen from first principles simulations

Area of Science:

• Condensed matter physics
• Materials science
• High-pressure physics

Background:

• Understanding the behavior of elements under extreme pressure is crucial for various scientific fields.
• Oxygen's properties at high pressures are not fully understood, particularly its electronic and structural transitions.

Purpose of the Study:

• Investigate the structural and bonding properties of dense fluid oxygen.
• Determine the pressure-induced electronic and structural phase transitions in oxygen.

Main Methods:

• Utilized first-principles simulations to model fluid oxygen.
• Analyzed structural, bonding, and electronic properties up to 180 GPa.

Main Results:

• Observed band gap closure in molecular liquid oxygen, indicating a transition to a metallic state.
• Identified molecular dissociation around 80 GPa in the metallic fluid.
• Found spin fluctuations significantly impact the electronic structure of low-pressure fluid oxygen.

Conclusions:

• Fluid oxygen exhibits a gradual transition from semiconducting to metallic behavior with increasing pressure.
• Molecular dissociation is a key event in the high-pressure phase diagram of oxygen.
• Spin fluctuations are critical for understanding oxygen's electronic properties under pressure.