Quantum Monte Carlo Simulation of the High-Pressure Molecular-Atomic Crossover in Fluid Hydrogen

TL;DR

This study uses quantum Monte Carlo simulations to investigate the molecular-atomic crossover in high-pressure fluid hydrogen, challenging previous predictions of a first-order phase transition.

Contribution

It applies the CEIMC method to fluid hydrogen, providing new insights into the nature of molecular dissociation under high pressure.

Findings

No evidence of a first-order phase transition was found.

Supports the idea of a continuous crossover rather than a sharp transition.

Quantum Monte Carlo offers a reliable approach for studying high-pressure hydrogen.

Abstract

A first-order liquid-liquid phase transition in high-pressure hydrogen between molecular and atomic fluid phases has been predicted in computer simulations using ab initio molecular dynamics approaches. However, experiments indicate that molecular dissociation may occur through a continuous crossover rather than a first-order transition. Here we study the nature of molecular dissociation in fluid hydrogen using an alternative simulation technique in which electronic correlation is computed within quantum Monte Carlo, the so-called Coupled Electron Ion Monte Carlo (CEIMC) method. We find no evidence for a first-order liquid-liquid phase transition.