Unexpectedly high pressure for molecular dissociation in liquid hydrogen by a reliable electronic simulation

TL;DR

This paper uses advanced quantum Monte Carlo molecular dynamics to reveal that liquid hydrogen remains molecular and stable at much higher pressures than previously thought, challenging existing phase transition models.

Contribution

It introduces a reliable simulation approach that accurately predicts the high-pressure phase diagram of hydrogen, showing the molecular phase's unexpected stability.

Findings

Molecular liquid phase is stable at higher pressures than previously believed.

Transition to atomic phase occurs at much higher pressures.

Low temperature atomization remains experimentally challenging.

Abstract

The study of the high pressure phase diagram of hydrogen has continued with renewed effort for about one century as it remains a fundamental challenge for experimental and theoretical techniques. Here we employ an efficient molecular dynamics based on the quantum Monte Carlo method, which can describe accurately the electronic correlation and treat a large number of hydrogen atoms, allowing a realistic and reliable prediction of thermodynamic roperties. We find that the molecular liquid phase is unexpectedly stable and the transition towards a fully atomic liquid phase occurs at much higher pressure than previously believed. The old standing problem of low temperature atomization is, therefore, still far from experimental reach.