Exciton Nature of Plasma Phase Transitionin Warm Dense Fluid Hydrogen: ROKS Simulation

The transition of warm dense fluid hydrogen from an insulator to a conducting state at pressures of about 20-400 GPa and temperatures of 500-5000 K has been the subject of active scientific research over the past few decades. However, various experimental and theoretical methods do not provide consistent results. In this work, we have applied the restricted open-shell Kohn-Sham (ROKS) method for first principles molecular dynamics of dense hydrogen after thermal excitation to the first singlet excited state. The Wannier localization method has allowed us to analyze the exciton dynamics in this system. The model shows that a key mechanism of the transition is associated with the dissociation of electron-hole pairs, which allows explaining several stages of the transition of fluid H-2 from molecular state to plasma. This mechanism is able to give a quantitative description of several experimental results as well as to resolve the discrepancies between experimental studies.

Automated summary

The transition of warm dense fluid hydrogen from an insulator to a conducting state has been a topic of active research with inconsistent results. This study used the ROKS method to simulate the dynamics of dense hydrogen after thermal excitation, and the Wannier localization method to analyze the exciton dynamics. The model suggests that the dissociation of electron-hole pairs is a key mechanism for the transition, explaining various stages and resolving discrepancies between experimental studies.