Study of distortion effects and clustering of isotopic impurities in solid molecular para-hydrogen by Shadow Wave Functions

TL;DR

This study uses advanced Monte Carlo simulations with Shadow Wave Functions to analyze how isotopic impurities like HD and o-D2 affect the structure and solubility in solid para-hydrogen, revealing impurity clustering and solubility limits.

Contribution

It introduces a fully optimized Shadow Wave Function approach combined with Variational Monte Carlo to study impurity effects in solid para-hydrogen, providing new insights into impurity clustering and solubility.

Findings

Impurities tend to cluster at certain concentrations.

Solubility limits for HD and o-D2 in p-H2 are estimated.

Impurity effects influence the excess energy of the system.

Abstract

We employed a fully optimized Shadow Wave Function (SWF) in combination with Variational Monte Carlo techniques to investigate the properties of HD molecules and molecular ortho-deuterium (o-D_2) in bulk solid para-hydrogen (p-H_2). Calculations were performed for different concentrations of impurities ranging from about 1% to 25% at the equilibrium density for the para-hydrogen crystal. By computing the excess energy both for clustered and isolated impurities we tried to determine a limit for the solubility of HD and o-D_2 in p-H_2.