Finite H2 concentrations in superfluid 4He

TL;DR

This study investigates the solubility of molecular hydrogen in superfluid helium-4 at zero temperature using diffusion Monte Carlo simulations, revealing clustering behavior at equilibrium density and potential for dilute solutions at higher densities.

Contribution

It provides the first detailed quantum Monte Carlo analysis of H2 solubility in superfluid helium-4, highlighting density-dependent clustering phenomena.

Findings

H2 molecules cluster at equilibrium density

Dilute solutions may exist at higher densities

Clustering prevents uniform solubility in superfluid helium-4

Abstract

We have studied the solubility of molecular hydrogen in bulk liquid $^4$He at zero temperature using the diffusion Monte Carlo method and realistic interatomic potentials between the different species of the mixture. Around the $^4$He equilibrium density, the H_2 molecules clusterize in liquid-like drops blocking the existence of a uniform dilution. On the contrary, at higher densities the cluster formation is less feasible and metastable dilute solutions may exist.