Towards the same line of liquid-liquid phase transition of dense hydrogen from various theoretical predictions

TL;DR

This paper uses advanced first-principles simulations to investigate the liquid-liquid phase transition in dense hydrogen, aiming to reconcile discrepancies between models and experiments, and estimates the critical point above 2000 K.

Contribution

It provides the most consistent first-principles calculations of the LLPT in dense hydrogen using path-integral molecular dynamics and improved density functionals, including quantum Monte Carlo methods.

Findings

Critical point estimated above 2000 K.

Metallization pressure aligns with the equation of state plateau.

Most consistent results among available theoretical models.

Abstract

For a long time, there have been huge discrepancies between different models and experiments concerning the liquid-liquid phase transition (LLPT) in dense hydrogen. In this work, we present the results of extensive calculations of the LLPT in dense hydrogen using the most expensive first-principle path-integral molecular dynamics simulations available. The nonlocal density functional rVV10 and hybrid functional PBE0 are used to improve the description of the electronic structure of hydrogen. Of all the density functional theory calculations available, we report the most consistent results through quantum Monte Carlo simulations and coupled electron-ion Monte Carlo simulations of the LLPT in dense hydrogen. The critical point of the first-order LLPT is estimated above 2000 K according to the equation of state. Moreover, the metallization pressure obtained from the jump of dc electrical conductivity almost coincides with the plateau of equation of state.