Nuclear quantum effects and nonlocal exchange-correlation functionals applied to liquid hydrogen at high pressure

Area of Science:

• Condensed matter physics
• Computational chemistry
• Materials science

Background:

• Understanding liquid hydrogen's behavior under extreme conditions is crucial for planetary science and fusion energy.
• Previous simulations often neglected nuclear quantum effects and used simplified functionals, limiting accuracy.

Purpose of the Study:

• To investigate the impact of nuclear quantum effects and advanced density functionals on liquid hydrogen's dissociation and metallization.
• To improve the theoretical description of molecular dissociation and phase transitions in dense hydrogen.

Main Methods:

• First-principles molecular dynamics simulations.
• Inclusion of nuclear quantum effects (NQEs).
• Utilization of nonlocal exchange-correlation density functionals (DFs) addressing self-interaction error and dispersion interactions.

Main Results:

• NQEs significantly affect intramolecular properties and dissociation.
• Advanced DFs provide a superior description of molecular dissociation and metallization compared to prior studies.
• Excellent agreement with experimental optical properties along Hugoniot curves was achieved.
• A first-order liquid-liquid transition was observed, with increased transition pressures (>100 GPa).

Conclusions:

• Nuclear quantum effects and sophisticated density functionals are essential for accurately modeling liquid hydrogen.
• The improved theoretical model aligns well with experimental data, enhancing our understanding of hydrogen under extreme pressure.