Onset of metallic transition in molecular liquid hydrogen

TL;DR

This study uses advanced quantum simulations to show that hydrogen becomes metallic at lower pressures and temperatures than previously thought, with stable molecular metallic liquid phase, challenging conventional dissociation assumptions.

Contribution

It provides new insights into hydrogen metallization, demonstrating that metallic liquid hydrogen can exist without molecular dissociation at certain conditions.

Findings

Metallization occurs at lower pressures and temperatures than molecular dissociation.

Metallized molecular hydrogen is stable over a wide range of conditions.

Challenges the assumption that metallization coincides with dissociation.

Abstract

Liquid-liquid phase transition of hydrogen is at the center of hydrogen phase diagram as a promising route towards emergent properties such as the Wigner-Huntington metallization, superconductivity, and superfluidity. Here we report a study on the liquid-liquid phase transition of hydrogen using the state-of-the-art diffusion quantum Monte Carlo and density functional theory calculations. Our results suggest that the metallization process happens at lower pressures and temperatures compared to the structural phase transition of molecular to atomic hydrogen. The consequence is that metallized molecular hydrogen is stable at a wide range of pressures and temperatures. Our study breaks the conventional assumption that metallization coinciding with dissociation of hydrogen molecule, and the molecular metallic hydrogen liquid phase is likely to become the frontier of studying hydrogen phase transitions.