Properties of Dense Fluid Hydrogen and Helium in Giant Gas Planets

TL;DR

This study uses density functional theory molecular dynamics to explore how helium affects the molecular-to-atomic transition in hydrogen within giant gas planets, revealing helium's role in stabilizing hydrogen molecules.

Contribution

It provides new insights into the influence of helium on hydrogen's molecular stability and structure in planetary interiors using ab initio simulations.

Findings

Helium stabilizes hydrogen molecules by increasing electron localization.

Hydrogen molecules are shorter and more stable in helium-rich environments.

The structure of the liquid mixture is characterized by pair correlation functions.

Abstract

Equilibrium properties of hydrogen-helium mixtures under thermodynamic conditions found in the interior of giant gas planets are studied by means of density functional theory molecular dynamics simulations. Special emphasis is placed on the molecular-to-atomic transition in the fluid phase of hydrogen in the presence of helium. Helium has a substantial influence on the stability of hydrogen molecules. The molecular bond is strengthened and its length is shortened as a result of the increased localization of the electron charge around the helium atoms, which leads to more stable hydrogen molecules compared to pure hydrogen for the same thermodynamic conditions. The {\it ab initio} treatment of the mixture enables us to investigate the structure of the liquid and to discuss hydrogen-hydrogen, helium-helium, and hydrogen-helium correlations on the basis of pair correlation functions.